top of page

Journey To Perfection - A Review Of The 64 Audio Nio, U12t, Trio, U18t and U18s

A super showdown of the top end of 64Audio's line-up - a journey through one company's pursuits, and my personal reflections as I weave my way through, searching for what moves me most.

***The following is the very first review I did, and my first post to Head-Fi, one of the world's premiere forums for audiophiles. It originally appeared April 21, 2021 - I feel it is still very relevant and so I feature it here now. I hope you enjoy! ***

Let me briefly introduce myself: I am a professional touring/studio musician, a producer, photographer, videographer and director. I am on the road A LOT, sometimes as much as eight months a year, and the solace I get when I listen to music during the tumultuous travel days and hectic nights has always been a necessary sanctuary for me. I live and breathe music, every day, all the time. I am incredibly eclectic in my tastes, but more on that later.

This is my very first post to Head-fi, and I am very happy to meet you all! On top of being a multifaceted artist, I am also an extreme audiophile. I mean that in the most basic sense of the word; I am completely and totally obsessed with music and the quality of the sound. It affects me deeply, stirring my emotions, taking me on a journey and even affecting my life in myriad ways like only music can. I spent my life in recording studios and on the road with bands, and I know first hand how artists put their heart and soul into their music, and how hard they work to make the final product as perfect as possible. What we end up receiving as “end consumers” oftentimes pales in comparison to what they meticulously crafted, and this always bothered me on a deeply personal level. Music, as it was intended to be heard, and felt, in my mind requires a certain level of respect. Attention must be paid to not only the process, but the heart that went into the creation. I know from experience that listening to my favorite mixes in a great studio, or on a great Hi-Fi system, in a perfectly treated room, on world class speakers, can be the most incredible experience attainable. It’s perfection. Where everything just sounds right, and as it should. There is depth and space, cavernous energy and explicit detail, nuance and flair, the tiniest subtlety. The kind of thing that moves you to cry, cheer, laugh, or dance with eyes closed in limitless joyful abandon. A space for the music to embolden your soul, where you have no choice but let the music overtake you. This is how music should be - and thusly - I feel this is how I wish to listen at all times.

Of course how we all hear music is an individual experience; everyone has different tastes, styles and desires for how their music is presented. Big bass, extreme levels of clarity, soft and sweet, super loud, absolutely reference, you name it. Some people don’t care much at all, and anything will do. Others like myself strive for the seemingly unattainable perfection of the holy grail of sound. Our environment is is also subject to change, we don’t always have the opportunity to just melt away - we all work, live, move around and have lives that require us to be flexible and aware of our surroundings - thus the creation of mobile high fidelity audio. After years of travel I realized that what I wanted, (and needed) was a portable version of that magical experience I got listening to a great home system, a way to relish in my music all over the world, at any time, on a plane or in the park, without resulting to blasting my neighbors into oblivion and/or waking up my wife at all hours. It needed to sound amazing, be comfortable enough not to bother my intensely sensitive self (more on that later on), and it had to be affordable. What I mean by affordable is, coming from the HiFi/Musician world - a working professional like myself simply cannot afford the stupid-crazy-insane expensive level of flashy-bragging-rights gear that only doctors, lawyers, corporate sponsored studios and the über rich can get. It has to be realistic on some basic level. All I wanted was a portable “perfect room”, is that too much to ask?

A quick word about ears. Everyone has different ears, be it their size, shape and fit - but also how they work - the act of listening varies greatly person to person. I know firsthand as an engineer and producer that many people simply don’t know how to listen. Their ears work fine, but they were never inspired to - nor taught to - really listen to music. To absorb its details, finding the nuances and subtlety in the mix, extrapolating the finest details and overtones, this comes with practice. (Many just don’t care and that’s also completely fine, consequently they probably won’t find much use of this article and can just go back to enjoying their music now without the worries the crazies like me have). I don’t mean in any way that people who don’t listen critically don’t enjoy music, quite the opposite actually. Most people can enjoy music very deeply with any old cheap headphones, any environment and gear is enough for them. But not for me - and probably not for you if you’re reading this. Our ears desire to be dazzled, to be blown away, to have a spiritual connection to the music, through the experience of listening to it, feeling it, knowing it, discovering it, and developing with it. Music deserves our respect and our attention, remember?

On a side note, I am a really, really picky person. The smallest details inspire me or drive me mad. I am extremely finicky and demand only the best in my work, and this makes its way into my choice for music gear too. I don’t claim to have better ears, or be a better listener than anyone - not at all. I simply spend my life in an environment and job that requires me to be intensely critical, analytical, attuned and aware of what is going on in the tiniest details. I know what I like, I know what I want, and I know what is possible from my years of experience listening on some of the best systems in the world. So the question became clear, is it possible to get the same level of reference quality, pure detail and lush energy in an IEM that I was used to in a studio situation or Hifi listening room? A tall order I felt, still do. So now you know where I was coming from when I embarked on my IEM journey. After reading every review on the planet - and getting some really good advice in the process from those that had already travelled the road before me - I knew I needed to hear them all for myself and make my own decision. “Hearing is believing” is the phrase yes?

What follows is my journey with the high end IEMs from 64 Audio, the company I was most interested in when I began this journey in earnest. I really wanted my first set of customs, and they were universally considered one of the very best in this wildly diverse field. There are of course myriad options when one embarks on a sound quest such as this, I simply felt drawn to them, they had intensely positive reviews, and their custom offering greatly interested me. After years of fiddling with tips, fit, seal and endless disappointments and irritations I was ready for my first set of customs. This was to be my LAST PAIR of headphones for a long time, and I wanted them to be perfect. So I found a dealer, made friends with them, and then paid a huge deposit to facilitate the opportunity to spend the required time with all the high end models for a couple weeks. I needed real time with them, in all aspects of my personal and professional life, just going to a store just wasn’t going to cut it. After trying their entire line of high end models for several weeks, I can honestly say that I know each of them on a deep personal level, and with this experience I will try to impart my thoughts and feeling on them, and the journey to making my personal choice to getting the final product in my ears.

Before we get started please keep a few things in mind:

1- I will attempt to be as complete, yet brief as possible, without skimping out on the details. I know the idea can be daunting, trying to figure out what to buy with so many different IEMs, and the outrageous price tag involved. I would like my experience to help others, in the way that other reviewers helped me.

2- I have no affiliation with 64 Audio. None. I decide to try the whole lineup on my own, found a dealer that would let me demo them all out at once, paid the deposit myself, and came to my own conclusions.

3- These are all extremely high end headphones, and they are all very expensive. For some this constitutes insanity to spend this kind of money on a headphone. For me, and those like me bitten by the scratch-impervious itch, the road to the perfect headphone is both an obsession, and a fabulous -if not sometimes painful- journey. So, when I say affordable or expensive after this, take this with a grain of salt and perspective.

4- All my listening was done on an Astell & Kern SE200 using my Flac collection of 24-96 or higher files. I have an enormous collection of 24-192 vinyl rips, SACD and MFSL recordings, as well as Tidal Master recordings saved to my player. My tastes are very eclectic and include but are not limited to: a lot of modern jazz and ECM records, Classic rock, old jazz, blues, fusion, rock, indie, folk and bluegrass, some metal, electronic, down tempo, well mixed pop, and some classical and opera as well. Everyone uses drastically different musical choices when testing IEMs and headphones. Make sure that the reviewer you’re listening to has similar musical tastes to you, otherwise their opinion might not be as valid as you would need. An IEM someone loves for their K pop jams might not inspire you for your Hendrix collection, etc.

5 - These are my personal experiences, so they are PERSONAL. We all hear differently, we want different things, and what I say and/or feel doesn’t mean that your experiences (or other reviewers) are not valid. Quite the opposite, if you love something and it moves you deeply, thats the only important thing. YOU are the only important variable here.

6 - All the 64 Audio IEMs sound really great. If I say that one is dark, or bright, or flat, or V shaped, or better or worse, take this all with a sense of perspective as well. (Remember also my sense of insanely fine tuned expectations) You really can’t go wrong with any of them and everyone’s experience will vary.

I used the m15 APEX module for all these tests. I find it to be the most balanced, while the m20 was too chesty and heavy handed, and the MX is way too open and loses most of its character and power. The APEX modules really do affect the sound quite a bit, mostly in the bass and soundstage areas. While I do hear more bass with the m20, the quality of the bass is not nearly as good. And you lose the vastness of the stage, and the separation of the instruments also suffers as a result. So, if you prefer more bass and thicker presentation then you should try the m20. If you like really open and spacious and linear you can try the MX but I found it basically unusable as it loses too much body. The m15 is all I use, it's the most cohesive and balanced. (The Trio and Fourte do not have swappable APEX modules)

So finally… let’s get started!

The U12T

My first listen was the U12t. From the first moment I loved the house sound of 64 Audio; the sense of space, the details and epic soundstage. The Tia drivers create a high end that is so ethereal and sweet, so micro detailed and yet smooth, I was hooked from the get go. They are an effortless IEM, doing it all with ease and class. Using 12 BA drivers per side, they are a master of soundstage and layering, with an emphasis on a lean and clean presentation.


While the U12t is touted as a soundstage monster, which it is, the bass steals a lot of the conversation. It’s deep, rich and reaches lower than one would expect a BA to go. It’s the first thing I noticed, it certainly grabs your attention with its boosted sub bass emphasis. I was instantly impressed with its punchy personality, its ability to boast detail and layering subtleties in the lowest regions, and an almost complete lack of that plasticky BA ickiness. Again, there is a definite sub-bass emphasis, with the lowest frequencies hitting you hard in the chest, felt and heard, but boosted a bit much over linear for my tastes. While the sub-bass is meaty, consequently the upper bass can feel somewhat lacking and distant compared to the sub bass regions, leaving the bite and meat of bass, low guitars and percussive instruments to feel a bit hollowed. There is a great power to the bass, but I can’t help but miss some of the meaty parts and not just the deep thump. The detail of the upper bass is there in spades, but the weight and growl of it is more lean and hollowed out. To be clear, this is the effect of the boosted sub-bass, and not some inherent lack of frequency presentation. Hip hop, electronic and well mastered pop music will benefit from this kind of a tuning, leaving a lot of space for the lower mids to shine in their slightly leaned out way. Classic rock has lots of power, with drums and guitars exploding with plenty of oomph, there is no bleed into the higher registers so the low end is nice and clean, good short decay and really, really nice layering. While these IEMs are touted as a reference tuning I think purists will feel the bass emphasis to be a bit too much. I really enjoyed the low end of the U12t, despite its somewhat lacking upper bass body weight. For most people this is BA bass at its best, and the deep sub bass emphasis does increase the listening enjoyment and fun factor a great deal.


The mids of the U12t are classic 64 Audio. A little on the lean side, but crystal clear and incredibly detailed. They have such a sense of space, but also a lot of emotion and vibrancy as well. The sound reaches very far in all directions, especially width in the midrange. Vocals are rich and detailed, instruments have great separation. The staging is more cool and distant than intimate, this is a huge stadium stage feeling and each frequency spectrum has its own space and freedom to move around without bumping into anything. Vast, well timbered, extreme detail, with a slightly leaner presentation. Again, for a critical linear purest, the mid range can feel slightly hollowed out here, leaner and cleaner than I would personally prefer, but perfect for those wanting an effortlessly clear presentation that is more on the open side. This is the tradeoff that the U12t makes, it sacrifices some note weight for openness and space. Snares and instrumental attacks have a lot of snap but not as much body, leaving them very detailed but less full. This is not to say that the U12t is thin, not at all, it’s just not a super fat and thick sounding IEM, especially in the mids. Precision, articulation, subtlety, dynamics, expressive and immersive, and slightly on the lean side. With heavier music, or mixes that were mastered on the bright side, I found the mids to a sometimes a bit unforgiving and too clean, analytical and almost cold which was surprising considering the U12t is considered slightly on the warm side. For me that tuning and signature was slightly towards the cooler side for the mids, again going for clean, vivid, and detailed over full, fat and natural note weight. For those that like a perfect lean and clean presentation, incredible details and vast stadium staging, the U12t is your baby.


64 Audio treble needs to be heard to understand. Their Tia driver system really shines, and gives all of their IEMs this effortless silky high end, with this sense of space and vertical soundstage that I have found to be unrivaled in other brands. Depending on the model it can be more or less forward, but there is always this sense of space, air, and magic to them with just the right amount of sparkle. The U12t is no exception, with a wonderful top end that oozes class and presentation. There is A LOT of air and space here, with a tiny bit of warmth to it allowing it to be incredible detailed but never harsh. The is sparkle and clarity, but not too much sizzle, never reaching into the ultra high frequencies with brutal force, instead opting to be controlled and smooth. The amount of high end is also perfect, they really nailed it for the U12t. For treble energy purists and serious sparkle aficionados this could be slightly subdued, as the tuning goes for a more natural and organic signature than over the top treble energy and sparkle city. I found the top end to be a joy to listen to, never sibilant, effortless in its presentation and reaching to the stars when given the right tracks. This is a high end for everyone, effortless and silky smooth, never tiring.

Personal Choice: This is a brilliant IEM, with a tuning that will please almost everyone. It’s vast, dynamic, incredibly musical and expressive. My only minor qualms are the bass tuning, and the slightly lean midrange. I suppose these are the sacrifices made for that enormous stage, the finesse, and the space in the mid range. I would have opted for just a bit more of a linear sub bass presentation to keep the entire IEM’s signature more even, but that’s just me. I do dig the boosted bass, just make the whole bass the same weight and we’re golden in my book. This IEM is definitely not “bright” but it’s not thick and beefy either, leaving me to feel sometimes that it was a bit more clinical than warm, though this has more to do with the Leander mids than anything else. It’s extraordinarily balanced, and lots of fun though. The U12t really is majestic, and for most people this is as far as one needs to go. It is frequently on many “best of” lists, and for the value, this is truly one the best IEMs you can buy. This deserves my highest recommendations if you’re on the fence.


The Nio is 64 Audio’s newest hybrid, using 8 BA drivers and a single DD for the bass. They are only available in universal, and they are 64 Audio’s “cheapest” high end offering. A somewhat sidestepped evolution of the universal only N8 model, they are certainly different and more cohesive sounding to my ears. They are a wonderful set of IEMs, marketed to be more fun than analytical and I can say that they accomplished this perfectly. They don’t have the same grandiose soundstage and clinical detail retrieval, preferring instead to go more intimate and powerful for a super fun listen. Some might compare this to the CA Solaris, and I would agree, though the Nio is more on the linear side, while the Solaris has more irregularities in its tuning.


The bass on the Nio is great, like really really great. That dynamic driver has great power and a very organic and vibrant tonality. There is a lot of energy there, without sacrificing layering and dynamics, and it digs deep and hard for a serious dose of low-end thumb. This is a very lifelike and organic bass, with plenty of overtones and realistic tonality. Its tuning is definitely elevated above linear, going more for power, depth and fun. The bass does bleed into the upper bass/lower mids a bit as well, so the entire low end is really powerful, with great texture, but it does sacrifice some clarity and space in the lower mids as a result. It isn’t congested at all though, just a very satisfying, pure and deep bass with loads of kick and slam. For quality I would put it up there as some of the best bass I have heard in an IEM. I did find that after extended listening the tuning was a bit too heavy-handed for me, leading to some fatigue and even a headache along the way, but bass heads and anyone loving great bass with a bit more energy will certainly be very happy here.


The mid range of the Nio is similar to the U12t, but less revealing and a little more thick and juicy. This tuning sounds more natural to me, with note weight and texture being more realistic and accurate. I hear more of the tonality of the instruments, but with less detail and smoother transients. The low mids have a little more body and warmth to them, more gristle and meat, and the upper mids are slightly fuller, and don’t shine quite as much as their more expensive brother the U12t. There is a bit less detail, less space, with the soundstage and tuning being more intimate and easy to listen to instead of the vastness of the U12t.

Instruments like guitars, and toms have more weight and power, albeit with less finesse. For the lower end of their lineup these mids, while being less surgical and detailed, I loved that they have this more correct note size and weight. I find myself getting lost in the song more, feeling the song a whole, rather than delving deeper into its intricacies like the journey the U12t gave me. There is still plenty of detail here, just not this IEM’s most prominent feature.


The treble on the Nio is a blast to listen to. Not in the same ballpark as the U12t, or really any of the other 64 Audio IEMs, it’s instead somewhat rounded off with less treble presence and air. That’s not to say that the Nio is dark, it’s just a less intense and less high end sound. It still has that Tia smoothness and some extension, and I think a huge amount of people will fall in love with the Nio for how much fun it is to listen to. It has the same quality of high end as the U12t, simply less of it. There is less space, less detail, and less grandiosity, but it gives instead a very easy and fun signature that will never leave you worried about a brightly mastered mix tearing your ears off. Somehow the level of detail still remains high, it’s more of the amount of treble that you notice being attenuated or smoothed out.

Personal Choice: I don’t want to give the impression that the Nio is dark, or boring. Far from it, it’s a wonderful IEM end that you can listen to all day, simply removing some of the surgical precision and detail in favor of a more rounded, full and warmer presentation that will never tire. While this is not THE IEM for me, I think many people will love it, and if I could afford more I would certainly have one as well. It’s a great matchup for the Solaris 2020, where you can easily see the different tuning and house sounds of 64 Audio compared here. Killer bass, fuller mids and an easier to listen to treble make the Nio a more mainstream based IEM than some of the others in the 64 Audio stable, but that doesn’t mean it’s not special and a blast to listen to. There is still great resolution and detail, just less so than the other models. For some the lack of a custom option could be a deterrent as well, but I can attest that this is also one of the most comfortable universal I have tried.


Let’s get this out the way immediately: the Fourte is plain bonkers! They are 64 Audio’s most expensive, and most advanced IEM currently available, and is the most outrageous sounding IEM I have ever heard. Using only 3 BA drivers and a single DD for the bass, with custom tuned sound chambers for each, this is one absurdly high resolution monster! This is the ultimate in performance Lamborghini of IEMs, with a price to match. Describing it requires a ton of superlatives, and a healthy dose of hyperbole to match. Superb. Ridiculously good. Maddeningly good. Godly even? It’s really something special, and if you like an added dose of treble energy and unbelievably enormous soundstage, this is the best IEM ever made. While they aren’t the most reference correct set out there, they are certainly one of the most impressive. Available only as a universal model, I was told with all the tuning chambers they would be near impossible to make in a custom form.


This is the best bass I have ever heard in an IEM. I’ve said it. The bass is crazy amazing, reaching deep, rumbling with authority and realism, while also having the best texture, separation, detail and layering I have heard. It is also incredibly organic, giving bass, kick drums, low keys, organs and synth parts a sense of supple texture I have not heard outside of extremely high end studio monitors. It has a very fast decay and gets out of the way completely of the other frequencies. There is no bleed whatsoever to the higher frequencies staying perfectly controlled down below. I was stunned to hear the level of detail these things retrieve in the lowest registers, it’s really crazy. The richness, refinement and overall prowess of the low end here is not to be underestimated. Bass-heads beware, while the quality is perfect, the amount may be slightly lower than you’d wish. Like a supercharged race car in the garage, just revving its engine - you know its capable of so much more if they just decided to let ‘er rip. Instead of full blast the bass is refined, beautiful and powerful, with just a hint of restraint. Its perfection is in the reserve, leaving you with a sense of “what if they let it go all the way”? The Fourte low end oozes class, and will still satisfy the most demanding bass aficionados. If you want the same bass but in an all out blast, albeit less refined and classy, the Trio may interest you instead.


The mid range of the Fourte is hard to describe. The soundstage is so huge that it rivals my home Hifi setup. From the first moment I heard them, they literally took my breath away. The balance is perfect, the space sublime, they are unlike anything you’ve ever heard in an IEM. There is so much detail and resolution you might just lose your mind. With just a touch of warmth and fullness in the low mids, the upper mids are left to soar glistening clean, a similar lean character and energy as the U12t, but with more forward energy and transient attack here. Vocals float. Like really float in air, hovering above your head with perfect weight and precision. I have never heard an IEM that presents vocals in this way, and it’s really magical. You can hear EVERYTHING. We’re talking crazy insane resolution, pulling apart records I’ve heard 1000 times to show me things I had never heard before. Sharp as a razor, reaching to infinity, yet somehow controlled, organic and smooth… It’s hard not to get carried away, but such is the sensation of hearing the Fourte for the first time. But there is a caveat- as all good things aren’t meant to last yes?

After some extended time with them, I began to find some exceptions in the tuning and presentation that some people might not like. For one, the leaner midrange from the U12t makes the same appearance here, but with an added dose of transient attack ad cut, so for those going for tonal accuracy and easy listening, this isn’t quite it. Also, the pure amount of detail and resolution is staggering, and this could be a little too intense for some. It’s so sharp and resolving, leaving the transients a little on the intense side, thought they are certainly always musical and never overly “bright”. There is just so much coming at you, from everywhere, and there is nowhere to hide. Snares have amazing bite and snap, but the body and note weight is leaner allowing that incredible space to shine, but also leaving some instruments on the thinner side. I would say this is even more so than in the U12t’s tuning. They are most certainly not a thin sounding IEM, but to be fair, after the initial shock of how crazy amazing they are, some may yearn for just a bit less of, well everything. If you can’t be without every detail possible and highly resolving monitors are your bag, then look no further, as this is really out of this world good.


The treble of the Fourte is magical. The tia driver just goes off into infinity, offering an endless sense of space in all axes; vertically, horizontally and depth too. It’s effortless, clear and remarkably detailed. The treble makes me feel I need to invent words to describe it. Like ridonkulous, or mindblastinginsanityballs. It’s unlike anything I have heard in any system, again rivaling extremely high end speakers and custom made studio monitors. It’s simultaneously surgically detailed and sweet, scintillating and crisp, just plain amazing really. One can easily run out of superlatives trying to describe it. Here is the caveat; (again) for some people the amount of treble, the forwardness and intensity of it, could be a problem. Some could say that the Fourte is bright, I would say that it simply has more treble energy than some might be comfortable with. The treble is silky, sweet, open and glorious, but it is intense. Listening for long periods of time can invoke a sensation of being lost in space, invoking really intense emotions you might not be prepared for. I cried on numerous occasions with the Fourte. It’s that good. Other times it gave me a bit of a headache, and my shoulders were tired from being so intensely flexed. If you love treble, and don’t shy away from a super intense listening where you want more and more, (and more) this high end simply cannot be beat.

Personal Choice: So why doesn’t everyone just buy the Fourte? Well for one it’s crazy expensive. Second, not everyone wants something so detailed, so intense, so treble forward all the time, myself included. Most of my demo period I was drawn to the Fourte over all others, and I was seriously considering buying one for myself, but in the end I chose not to. For one, I really wanted a custom so I wouldn’t ever have to think about fit and tips ever again. Second, I will admit that I found the forward treble tuning, and the ultra extreme resolution of everything to be just a bit too much for me. After the initial shock, awe and unintended blasphemies of how incredible they are, I found that I had a hard time to relax with them. The leaner midrange also made its way into my mind, where instruments just didn’t have the accurate note weight, rightfully sacrificed for that ridiculously huge soundstage. Honestly, they could be a bit fatiguing - I knew they have endless potential, but instead of being excited to try new albums out on the Fourte, I was instead cautious they could be too much. For my work they are not accurate enough, and I couldn’t imagine using them on stage ether. So, for that kind of money it needs to be perfect, perfect for all my varied musical tastes. I know I am somewhat treble sensitive, and I know that for some the treble energy will be PERFECT. For those that have the money and love that treble energy, there is simply nothing more resolving and spacious on the planet available. Color me deeply impressed, but ultimately my hard earned savings went to my custom 18t instead. If someone gave me a pair of the Fourte, I would enjoy them deeply, be blown away by them everyday, and couldn’t thank them enough for the gift!


The Trio was presented to me as a somewhat simplified, cheaper version of the Fourte, and a step above the U12t. Using three total drivers, 2 BAs and a single DD with similar tuning chamber tech like the Fourte, it is again a remarkable feat of engineering and for a lot less money than the Fourte, though it is by no means cheap. I was quite curious to hear how the Trio would compare to the “nearly perfect” Fourte, and the somewhat similarly priced U12t. The idea of a Fourte style open and spacious tuning with a bit more bass sounded like a match made in heaven. In the end, the Trio was somewhat lost on me, with its exaggerated U tuning, crispy crunchy treble, and less than realistic timbre. I found it less appealing than its related siblings, just less real and enjoyable to me. I never quite got into it, and no matter how hard I tried I simply could not fall in love with it. But everyone has different tastes, and the Trio could check off many boxes for a lot of people.


The Trio’s bass is the first thing I noticed. It does indeed remind me a lot of the Fourte, reaching perhaps even a bit deeper than its more expensive brethren. It has similar abilities, great layering and resolution, and that same wonderful organic texture, but the tuning is more upfront and aggressive. There is simply more of it, all over the bass spectrum, which tends to bleed more into the upper bass and lower mids, leaving the bass sounding more lifted and the entire lower spectrum spotlighted instead of the perfect balance that is the Fourte. The decay is a bit longer, and while I felt the hits in my chest, the bass is more unbridled, with less sense of control. I found the finesse and grace of the Fourte somewhat lost in the Trio, exchanging it for more of that bass-head, over the top tuning. That feeling of a race care in the garage I felt with the Fourte - the excitement of knowing that there is more untapped power under the hood - this feeling isn’t present with the Trio. Everything is more out in the open, no-holds-barred, and it ends up being a little over the top for me. While the quality is really great, the tuning is just a bit too much and one ends up being somewhat pulverized with the bass and its heavy-handedness, especially in the upper bass regions which can be overwhelming.

Remember, I am speaking from the standpoint of reference, or more linear tastes here, and your mileage will certainly vary. This is more the boosted bass that takes a while to saturate your mix, as opposed to something you hear immediately, that’s way over the top leaving your mix unexpressive and bass dominant. After longer listening periods I just always wanted 20% less. The Trio is certainly NOT a nuclear bass canon, it wasn’t built just for bass, but it’s over the line for me. But, if you are a bass head junkie and love a heavier handed quantity, this is some of the best bass you can find.


The mids of the Trio are similar to the U12t, but even a bit more lean, especially in comparison to the boosted highs and lows. They are very clean, very spacious, with a huge soundstage, perhaps even a touch bigger and wider than the U12t. Similar to the Fourte, though even more so, the mids are leaner and crisper than I would prefer, opting more for that Head-fi modern sound, leaving me wishing for a little more realistic note body and weight. I prefer more of an organic timbre to instruments, where I can really here the tone and materials of the instruments, instead of going for maximum clarity and ultra fast and crisp transients. There is a huge amount of detail here, and nice layering, though I found the Trio to be on the aggressive side, and instead of being lush and organic it came off a bit too clinical or crispy. That is not to say the Trio sports an aggressive tuning, simply coming from the Fourte it’s just not as natural and organic, sounding more forced. Coming from the U12t, I would say there is a slight sense of warmth in the lower mids of the Trio, which does impart a nice send of body, but the upper mids are so leaned out that it is less euphonic and natural than other 64 Audio models.

After many listening tries, I couldn’t help but be reminded of the way Bose headphones are tuned, that exaggerated U tuning, where everything sounds polished and poppy, and in an effort to make everything sound “Bose” you are left with this processed/altered unnatural feeling, no matter how organic the original mix was. That may come off as harsh to some, and I don’t wish to be, so again keep in mind where my options are coming from and take it with a grain of salt. For clarification, the Trio is not a scooped tuning, as the mids are neutral, just the boosted bass and heightened treble energy give a feeling of this.


When I was researching about the Trio I heard quite a few reviewers mention that the high end could be somewhat crispy, and I am inclined to agree. While the U12t had this wonderful organic and easy treble, the Trio aims to be more energetic and modern, likening to the more expensive and lavish Fourte, but somehow ends up being less enjoyable. While the Fourte can be intense, it has this wonderful organic velvety lushness that seemed to come about naturally, while the Trio seems slightly forced. While it’s not painfully bright, it’s more bright than I would prefer with plenty of sparkle and pizzaz for those that prefer that sort of thing. Of course, I am splitting hairs here, and that tia driver still performs remarkably, giving that air, space, sparkle and soundstage 64 Audio is known for. This is clearly personal presence, and I am aware that many people prefer their treble this way.

Personal Choice: I realize that I am having a hard time finding the right way to describe the Trio, perhaps ending up being harsh or critical. I just feel all the 64 Audio models I tried were subtly varied, yet they all had this wonderful organic and “honest” sound signature quality to them. I was a little bit lost with the Trio. With the U shaped emphasis; the mids lean and clean, the low end’s boost and bleed into the lower mids, and that crispy high end, somehow the cohesion of the whole package just never quite settled for me. While the emphasis was clearly to make a more affordable Fourte, it seemed contrived and forced rather than effortless and sublime. I can imagine it’s very difficult to make something as amazing as the Fourte somehow “less”, and I can see how the result of those efforts gave us the Trio. For a lot of people this type of tuning will be perfect, I am happy to admit that I am probably in the minority here. For my tastes, this was the furthest from a reference tuning I heard in the 64 lineup, and the least “believable” if I could be so bold. The fact that it doesn’t come in a custom option was further affirmation in making my choice that much easier. I do see what they were trying to do, for me it just falls short.


Again, let me get this out of the way; the 18t is astonishingly good. Ridiculously good. While just the idea of 18 drivers in an IEM is crazy, and after hearing what the outlandish Fourte was capable of, I was skeptical how they could possibly keep up by adding even more drivers. More doesn’t always equal more in my book, but I had high hopes. I had read that the 18t was just the 12t but with less bass and a more reference tuning, and weirdly, I had this idea in my head that they had created something that wouldn’t be any fun to listen to - some piece of ultra-linear-outrageous-driver-war propaganda - to fool the filthy rich into buying more IEM than anyone would ever need. I was picturing Yamaha NS-10s, speakers that appear in every studio that painfully show all problems in a mix, with zero fun factor. Boy was I wrong. Take the wow and detail and crazy of the Fourte, but make it completely balanced, without a shred of oddity or a single frequency out of place, lower the slightly boosted treble response but keep the detail and space, then make the note weight and size COMPLETELY perfect, and now you are listening to the 18t.

The 18t is without a doubt the most amazing, accurate, fun, reference, spacious and incredibly versatile IEM I have ever tried. It places music exactly as it was recorded - with a pitch black background - on a silver platter right in front of you. And it’s happily available in universal or custom. This isn’t just adding more drivers to the already great U12t, some spec-maxed out atrocity, or a mishmash hybrid that sounds impressive on paper; this is a different level altogether. This sets the bar way above all others, and in my opinion 64 Audio have created the “perfect” reference monitor. I was hooked instantly, and knew my journey had come to a close.


I was expecting the bass to be subdued, playing second fiddle in an effort for more linearity and a reference tuning. But honestly, the first thing I noticed when I tried out the 18t was the bass. THAT BASS! It’s the best BA driver bass I’ve ever heard, and easily keeps up with most DD setups. While a BA system will never quite have the same level of texture and organic qualities, the balance, speed, power and compete control you get here with 8 BA drivers just for the bass is incredible. It reaches really, really low, endlessly low really, never breaking a sweat. It just goes DEEP. It growls when you want, blasts if required, and also never intrudes on a single other frequency, ever. True, it may have a hair less in quantity compared to the U12t, but it’s so much more lively, full and powerful that I would never say it was less. Gone is the missing upper bass from the U12t, and instead the entire bass range is full, rich, deep and perfectly tuned. There is absolutely no plastic BA sound, it really sounds like a dynamic driver, rolling out low end in spades of organic, layered and clean bass with incredible resolution at the same time. There is zero bleed to the other frequencies, and the decay and speed is incredible. Like everything on the 18t, it is just effortless in its presentation. Synths have power and drool with texture, cellos can purr or scream, you can hear the bow rubbing on the strings while also feeling the sub overtones in your chest. Kick drums have perfect oomph, attack and power, all balanced and clean. The low end of the 18t sounds, and feels, exactly correct.

I never felt a lack in either quality or quantity here which was a pleasant surprise and contrary to a lot of what I had read. It’s super fun, tonally accurate, and dripping with character, timbre, layering and natural organic goodness. I was blown away; the star of the 64 Audio lineup has killer bass for days that is just as fun as it is accurate…color me impressed. And you always feel like there is more in reserve, just waiting for you to open it up. There’s that race car feeling again, simultaneously showing reserve and unbridled power. *For those that prefer quantity over quality and simply must have more bass, (lots and lots) this will not be enough for you, but anyone else I think you’ll totally fall in love with the Tzar low-end.


Finally, finally!!! The 18t has the correct weight and note size in the mids while not sacrificing a single iota of clarity, detail, or texture. The mids are perfect, shockingly so. They have more resolution, more finesse, and more detail than the U12t, with an even more monstrous soundstage. Similar even to the Fourte in terms of detail, but much more accurate and correct to my ears with nary a weird frequency, or that feeling of enhanced space at the expense of realism. What strikes me in the heart is the bare reality of the presentation. The lower mids have a similar weight and girth as the Fourte, but the difference comes clear where the Fourte opts for the more lean and crispy upper mid, the 18t happily extends its perfectly weighted note body upwards. Upper mids have body, but are never fat or thick, just natural. This keeps things realistic and tonally correct, with snares, horns, percussion and guitars having perfect amounts of details AND body. Snares crack and hit, guitars cut, gleam, crunch and slam. Vocals are perfectly balanced, sitting forward and floating above your head, but without any sense of disillusionment and altered tuning to create a false sense of space. It somehow does all this while retaining the same level of resolution and detail as the Fourte, without any of the not so natural after effects it uses to achieve them. Words like razor sharp, surgical and freakin’crazy come to mind when trying to describe the mids on the 18t, but what you come away with is this sense the music is presented the way it was intended to be, by those that put their heart and soul on display when they recorded it.

The 18t has one of the largest sound stages of any IEM I have heard, end quote. Massive, wide, deep and tall, but never feeling overly spaced out, kind of intimate and immense at the same time. They’ve somehow created an IEM with incredible amounts of detail, layering and space, while also having the most tonally accurate tuning. Nothing is chesty, clouded or thick, nor is it overly lean or crispy, it all just sounds the way it should, while simultaneously creating this enormous amount of space, where all the frequencies live in harmony. Detailed, correct, dynamic, vast, intricate… the word I would use is “perfection”.


Here is the 64 Audio Tia driver at its best. Effortlessly the treble reaches into the stratosphere in all directions, always silky and never sibilant. Somehow there is more detail and resolution, more space and air than the U12t, and similar to the Fourte, while also being more enjoyable to listen to than either of them. Like a lot more. Transients in the upper registers are both clean and sweet. The amount of treble energy is perfect, allowing me to hear things I’ve never heard before in my favorite albums and discovering new ones without it ever being too intense. There is gleaming sparkle, but it never smashes you in the face, the presence and subtlety is magic here. The tiniest details are laid bare, begging you to find them, glistening off that pitch black background. The attack of a cymbal, the licking of lips, clinking of nails on the ivories, a fading violin panned hard left, they are gently presented to you on a golden platter, instead of forced on you like so many high end offerings do. You can hear everything, with incredible amounts of air and space, but there is also a sense of intimacy that baffles the mind. Again, this razor sharp precision, surgical quality is in the treble too, but it’s always sweet and clear, clean and effortless, never, ever too much. Velvet, high class, effortless high end that floats up unimpeded to the heavens, seemingly without limit, taking you along with it.

Personal Choice: This is what I had dreamed of, but thought wasn’t possible. Effortless, dreamy, impactful and powerful, but without breaking a sweat. No matter what I throw at it, the 18t excels, always letting you know that it’s comfortable and relaxed, with plenty of power in reserve. It simultaneously gives you incredible surgical detail, letting each and every little micro movement wash over you in a rain of sonic beauty, while also allowing you to just forget you’re wearing headphones and the music can take you on the journey the artist intended. While the Fourte immediately impressed me beyond words, after some time I found the irregularities and limit pushing to grate on my ears and mind. The 18t was also immediately impressive, giving me the same feeling of awe, shock and guffaw, and yet the longer I listened to them the more I fell in love with them, how perfectly balanced they are, and how crazy awesome they sound with everything. Not a single thing out of place. It’s the only IEM I have heard that gives you both; Intimate and arena. Detail and enjoyment. Reference and fun. Polished and groovy. Vintage and modern, hifi and Mp3, heart-pounding wow and jaw dropping balance. This is exactly what I wanted; studio quality speakers, in a perfectly treated room, right in your ears and ready anywhere, anytime. WOW. I ended ups ordering a beautiful set of 18t customs, which you can see in the photos at the end.


This is 64 Audio’s newest creation, and it resembles the 18t, but with a slightly different tuning for a different audience. The S stands for Stage, and as I understand it, this model is for people who might want the amazing technical abilities of the 18t, but with a fuller, more reserved and easy tuning, and for loud stage use. They have a little more bass, they can be played louder with wireless packs and crazy sources a touring musician has to deal with, and have a thicker, fuller sound that could be easier on the ears for long, loud concerts. In my experience they seemed to lack some of the magic the 18t has -that incredible staging and space, razor sharp perfection and unparalleled musicality- the 18s seemed almost dark and overly full in comparison. While it is a newer model, this definitely is NOT an upgrade, rather more of a side step. Honestly, I spent less time with this model, simply because for whatever reason it never quite clicked for me. But, as we saw with the Fourte, everyone has different wishes, and for some the surgical precision and clarity of the 18t could be too much, as the Fourte’s amazing yet intense presentation was too much for me. For people who find the 18t too revealing and/or intense, they might consider the 18s instead, and given the (S) stage moniker, touring musicians are a likely target audience here. I had a dealer demo universal unit for testing, but there is a brand new universal model that looks really lovely, as well as the custom option of course. I will say again that I tried my best to give the 18s a full go, but similarly to the Trio I never connected to it, especially when compared to the 18t.


Bass is similar to the 18s, but with a touch more body, more power, and a slightly stronger tuning. I’ve heard that some people found the bass tuning of the 18t to be a bit on the shy side, so this has been addressed in the 18s. If you ask me the 18t bass is still above flat and loads of fun, allowing the whole IEM signature to be more even and open, but that’s just my opinion. The technical abilities are exactly the same as the 18t, I hear the same voicing, resolution, layering, and beautiful tone, there is just more of it. I said that the 18t has the best BA bass I’ve ever heard, and the same could be said for the 18s, it really just depends on the tuning you prefer. They both reach incredibly deep, have endless levels of grunt and oomph while also showcasing texture and details even in the lowest registers. There is perfect separation between the registers with zero bleed, very fast decay and wonderful balance and authority. Power and detail are two very different things, and if you feel you need more belly shaking, well 64 Audio has you covered here with two similar models of modestly shifted bass levels. I think anymore wanting great bass would be tickled giddy with either of these, but the 18s does have more, perhaps at the expense of a fuller and less open presentation.


The differences become more apparent in the higher registers, as the mids here have slightly more body and weight to them, becoming more powerful but losing some of their delicate nature and subtlety. There is more bam and thwack, more power and drive, but less finesse as well. There is about the same level of detail, but it is presented in a different way, and I found it to be more full sounding, slightly congested even, especially compared to the open and effortless free flow of the 18t. The upper mids similarly have less air and openness to them, instead sounding fuller and more powerful but losing some of the wispy elegance of the 18t. Vocals are richer but still clear, instruments still have wonderful separation and detail but opt for a more full feeling with less air around them. I know it’s ridiculous to say, but the 18s made me feel a bit claustrophobic, always wishing that there would be a little more room to breathe. The perfectly tuned razor sharp attack and mind melting musicality of the 18t is now somewhat more “common” sounding, instead moving towards a more polite, smooth and “less tiring” signature. Transients are smoother, lines less clear in the sand. They have certainly built a very powerful sounding monitor, but in casual listening I never needed such power, instead I always felt the need to turn these up a few notches above the setting I used for the 18t or Fourte. These are still world class monitors with a big sound stage, but it just doesn’t compare to the 18t for me.


Treble can be a hot topic of discussion, especially among HiFi nerds and headphone aficionados; some believe that more is better; more sparkle, more brilliance, more technical power is better. Some prefer a smoother easier listening option. 64 Audio here chose to go in the later direction, giving the 18s a beautiful albeit tame high end. The treble here is a continuation of that mid fullness we found below, with similarly slightly attenuated levels of sparkle, clarity and air and slightly fuller notes going all the way up into the higher registers. The quality of the treble is the same as the 18t, but simply less of it, and less space that usually goes along with that openness. While the 18t gleams and shines and screams and cries, the 18s does, just less so. Details are more hidden, folded into space instead of projected to the forefront of your mind. Small details don’t leap out, details are somewhat hazed over. It’s more tame, more thick, more relaxed. I would imagine technically their sound stages to be very similar, but in practical use the soundstage of the S felt very different, it just wasn’t as illustrious and grand, feeling more closed in. It could be called a bit of a dark IEM, with a signature that will certainly not tire you, but also might not wow you either.

Personal Choice : Again, to each their own, and if you plan to spend every night on stage at high volumes this could be there better choice. It left me kind of wanting. I found less of an emotional connection with the signature, and always found myself wanting more, no matter how many times I came back to it. Some might appreciate its ability to create a “complete” sense of the music, letting you rock out to the whole, instead of the spotlight on details. Again, I found it lacking, at least in comparison to the 18t. One day I forced myself to use only the 18s all day, and just never got into it. The 18s should be considered a different approach, and NOT an upgrade to the 18t. BUT, If you find the 18t too revealing, then the 18s could be for you. If you like a thicker darker signature, again this could be the IEM for you. If you play live all the time and need something geared towards an easier listening mix, or simply want something with more bass and power than the 18t, this could be the ticket. This is a personal feeling and some people will love the S more than the T. My good friend is absolutely in LOVE with his 18S, so there you go. You need to try it for yourself.

A Brief Round-up...

As I’ve said, when shopping for the ultimate IEM it really comes down to personal preference and tastes. All of these sound great and their differences accentuate the strengths that different people might want and wish for. There is something for everyone here, and I think it plays well for 64 Audio to have such a diversified and epic lineup. They all have that trademark 64 Audio house sound, but they all have their own distinct tonality as well. If you’re thinking of buying a new monitor, you really should find a way to try them all out for yourself. But in lieu of that, and with no regard to price, here are some basic takeaways:

- Easier listening, warmer fuller mids, linear and cohesive, great bass: Nio

- Vast soundstage, more distant and arena tuning, clean presentation, classy and timeless: U12t

- U shaped modern signature with great bass and more treble energy and sparkle: Trio

- Perfect reference monitor with surgical precision and impeccable balance: U18t

- Stage reference monitor with easier listening and more power, slightly more bass than the

18t: U18s

- Absolute bleeding edge sound, extremely large soundstage, crazy detail and resolution with enhanced treble energy: Fourte

A word about customs

If you’re like me and had never owned or tried customs they can be absolutely amazing. When the fit is good, it’s unlike anything you’ve used in a universal, and the sound can be better, more consistent and solid than a universal as well. But, and this is a BIG but, the road to customs is potentially perilous, and could end up being more complicated and painful than anyone would wish for. The internet is rife with horror stories of refits and sadness for a lot of those that make the effort to get customs. Universals have better resale value, and due to the fickle nature of audiophiles, if you’re prone to changing your mind often, sticking with universals might be the smarter option. That being said, I don’t think I’ll ever buy another universal IEM, the listening experience of customs is just too good and the result is worth the risk to me.

As I hinted at earlier, I am extremely sensitive and that translates to fit as well as sound. The smallest movement or intruding poke can drive me absolutely bananas. Having something in my ears that doesn’t feel right, or doesn’t seal removes the enjoyment of the music for me completely. As one might expect from that preamble, I had some fitment problems…

I decided to get customs during the beginning of the COVID pandemic, and since I am living in Prague now, (Los Angeles was my home for 15 years) and since Czech doesn’t seem to have a CIEM scene at all, I couldn’t find an audiologist to do the impressions. I ended up having to drive to Berlin to Headtek; 64 Audio’s dealer there, a measly four hour drive, avoiding the lockdown conditions and slipping over the border undetected. It was a fun experience, and I was glad that I went because I also got to meet the head of HeadTek Micheal Hudson, who is the sweetest guy you could ever meet. We hung out, talked shop, and then he took me to their audiologist, who was very nice and seemed to know what he was doing. But what I know now, from painful experience, is that the quality of the impression - as well as it being done exactly the way the IEM company you’re using requires - is paramount. 64 Audio recommends using a 1” bite plate, and the audiologist just told me just to open and close my mouth like I was lightly chewing during the entire time the impressions were hardening. I didn’t know better. So, I was stoked, chatted some more with Micheal as we scanned the impressions, they were sent off to USA, and I drove home again evading the authorities, excited that I would never have to worry about fit and tips again. I even paid the rush service because I was so excited. When I got my first CIEMs a few weeks later, I was dismayed to find out that they didn’t seal well, and were so deep that they touched the inside of my ear canal painfully. Not knowing how long the “get comfortable with them phase” was supposed to last, I pushed it too hard, my ears were swollen and hurting so bad I couldn’t listen to any music at all for a few days and was understandably concerned about my new purchase. Ouch.

With me being in Prague, and with shipping, customs fees and endless waiting, this had all the signs of a potential disaster. But right away, I will say that I was completely floored by the customer service from 64 Audio. They went so far out of their way to make this right for me I couldn’t believe it. I was put in touch with Kalani, and this guy was so cool about it all. He reassured me that they would fix this, even when we had realized that the bad impressions were the culprit. He spoke to me for hours about my options, never got frustrated or annoyed at the barrage of questions I had about the smallest details, and was just so friendly and accommodating I was amazed. I needed new impressions, but he offered just to make me another set from scratch, and I didn’t have to wait for the old ones to get shipped back! So back to Berlin I went, got a new set of impression made, (this time closed mouth and 1” block just to be sure) and again I drove home excited that my journey was over. Again, they didn’t fit right, while they weren’t painful they didn’t seal well. Again Kalani offered to make me a completely new set, he even let me keep the old ones (that didn’t fit quite right, but were totally useable), because he said he felt bad about how expensive it would be to ship them back to them. Talk about customer service! They decided it was best to send me empty shells to test, and after three different sets of back and forth and small adjustments, we finally got them to a good fit. I told you I am really picky and really sensitive. Kalani never hesitated when I asked for yet another set with the smallest of tiny adjustments made, they really do care about getting you a good fit. I even felt embarrassed for how picky I was being, but Kalani just laughed and told me the only important thing was for them was to be awesome for me. How cool is that! So, 4 months after I took my first impressions they built the final IEMs to the test shells I liked the best, and they arrived at my door in Prague.

What a journey! What for some people I am sure is nothing more than a half hour visit to their local audiologist and a few weeks wait finally took me over 4 months, and 6 different refit adjustments. I’m not surprised, given my intolerance for error, and my sensitivity to perfection, I think I got off easy. I probably owe Kalani and the whole team a fruit basket and an apology gift card at this point to be honest. They were so cool about it, and in the end I actually have two sets of IEMs. It's amazing to have a backup pair, even if they don’t fit perfectly it’s useful for stage when I need to hear a little more of the band or my surroundings. 64 Audio truly stands behind their product, and they will move mountains to make it right. If you’re thinking about customs, having a company that you trust makes all the difference.


So was it worth it? Absolutely. I set out to find a set of IEMs that brought me joy, comfort and the ability to transport me into my music anywhere, anytime. I wanted a private music room in my head, where the treatment is perfect and everything just sounds right. I ended up pairing my 18t’s with an Effect Audio Janus Dynamic cable, (after market cables are a whole other thing and need to to be addressed in a different article entirely) and this setup is CRAZY GOOD. Like ridiculous good. I wanted a portable version of my home HiFi and this really nailed it; these are the escape I was dreaming of. I wear them all day, every day, and they amaze me every singe time. They are huge sounding, lush, delicate, intricate, beautiful, musical, expressive, honest and super, super fun to listen to. I head-bob like a madman on the tram, rock out on flights, and I can even do some basic mixing for work as well. I honestly didn’t think I would find something I loved so much, or that was so beautifully crafted (the intricate tiny driver work on the custom stuff is mind-blowing). That feeling of sitting in a studio with a monster set of Focals or a wicked Hifi setup of high end Dali’s, and just allowing that enormous - yet perfect mix - to wash all over you. Then bring that perfect studio setting to an 18 hour layover in Jakarta, or in the subway in Queens, walking to work, or bouncing around the back of a bus in the mountains of Nepal - that’s what I wanted. Just connecting to out music in a deep way, isn’t this what we all want? This perfection will be a little different for everyone, but for me, I have found my magical combination. Better than magical, if had to describe it in one word, it would have to be “perfect”.

Thank you for taking the time to read such a long article, whew! I hope that it was helpful, informative, and not too painful to get to the end. I really appreciated all the reviews I read, and I hope that this could possibly help someone who was in the same situation as me.

A huge thank you to Michael Hudson at Headtek, for his patience and joy, and for being just one of the nicest guys one could meet. Thank you to Tabitha Adams at 64 Audio’s refit department for being so accommodation to me. And a huge thank you to Kalani at 64 Audio for being such an awesome nice person, and for never making me feel like I was crazy, no matter how hard I tried. Nothing was ever a problem, no adjustment or question too small or stupid, and for making this “impossible to satisfy guy”, completely satisfied!


Rated 0 out of 5 stars.
No ratings yet

Add a rating
bottom of page