64Audio U12t

General Information

The 64 AUDIO U12 Universal-Fit earphones with patent-pending tia™ technology provide the ultimate personal listening experience for audio professionals and the most discerning audiophiles. Incorporating the tia single-bore with 4 low drivers, 6 mid drivers, and the incredibly smooth tia high and high-mid drivers improves the already lively and three-dimensional soundstage. The tia high-driver, located just inside the sound stem, completes the highs with a clean, smooth, and beautifully extended top-end. Lower-mids were masterfully refined while the low-frequency response remains intact, providing the familiar, warm and engaging sound of the U12. A protective mesh covering the sound port resists debris while the patent-pending apex™ module technology allows for customizing the sound signature and reduces air pressure inside the ear canal for fatigue-free listening. All of this technology is housed in an ergonomic aluminum shell for unmatched durability and beauty with a gorgeous brushed aluminum faceplate. The U12 with tia technology stands head and shoulders above the competition, offering a far superior listening experience with an immersive sound and impeccable spatial imaging.

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100+ Head-Fier
Pros: - Phenomenal detail retrieval across all frequency ranges
- Refined and musical tuning
- Top tier staging and imaging capabilities - great depth and accuracy
- Excellent dynamic range
- Best in class BA bass with great extension, presence, and suprising amount of slam when called upon
- Natural, smooth, and clean midrange
- Best treble presentation I've heard in an IEM
Cons: - Packaging and accessories are not good
- Some might find vocals slightly pulled back depending on the track
- Treble is amazing but not entirely "neutral"


Okay here we go!

The 64 Audio U12Ts are my favorite IEMs to date. I'm not afraid to say it. I wanted to mention my love for them at the start for fear as I'm writing this of encouraging people to go out there and spend... $2,000 on an in-ear monitor, which by its very nature is an audio category inherently limited by form and function. For the sake of full disclosure, I was able to purchase these second-hand for around $1300, which may potentially skew my perception of their "value." That being said, I'm not going to get too paternalistic here. If you have the means and you want a phenomenal IEM, I'd highly recommend this one. Alright let's get into it.

Cable and Accessories:


I came very close to docking these IEMs a half-star based on packaging and accessories alone. Ultimately, sound triumphs over all, but the packaging and accessories here are straight up bad.

I guess let's start with the case. Not only is it bulky and difficult to handle, but it also barely even fits the iems with a cable. Further, the inside of the case is made out of hard plastic, which is not really the material I want my $2k IEMs bouncing off of every time they're in there. Just not good. Honestly, I'd rather use a $3 case off Amazon.

Moving on to the stock cable, I'm just flabbergasted that this is what they included in the box. I had heard it was bad, but I didn't know it would be completely unusable. God-awful memory wire, bad microphonics, discomfort, and tangling. It's an absolute mess. I can’t imagine that even those using this IEM as a stage monitor would find this cable serviceable. It’s a bit inexcusable at this point. I think 64 Audio know this though as it seems they are providing some better accessories in their newer models such as the U18s. Anyway, if you're going to get these, also get yourself a $15 Tripowin cable, or a $2000 fancy one if you're into that kind of thing. Sorry for the rant, just had to get that off my chest.

Build Quality and Driver Configuration:


Thankfully, the actual build quality of the IEM’s shells feels excellent. They are light, but very solid in the hand with a smooth aluminum finish that feels premium. I've also noticed from general use (and sometimes misuse) that they are pretty scratch and dent resistant. I’m a fan of the understated look since I’m not into flashy IEM shells. Though I am aware that some may find it a little boring. In terms of comfort, the U12Ts fit me better than any IEM I've tried in the past. Of course, this is a super subjective impression, but I thought it was worth mentioning. I can wear these forever and I’ve fallen asleep multiple times with them in.

As for the driver configuration, the U12Ts have 12 balanced armature drivers on each side. This includes 1 tia high, 1 high-mid, 6 mid, 4 low. That's a ton by any metric. While I'm well aware that driver count is not necessarily indicative of better sound quality, the U12Ts drivers are expertly integrated, surprisingly coherent, and the benefits to resolution are immediately apparent. On that note, let's get into how they actually sound.



All my listening was done with the M15 APEX module since I do not have the other modules on hand. In terms of critical listening, I primarily listened to them off my Cayin N6ii with the E01 motherboard. I also frequently used them for gaming and took them out and about using an iPhone dongle. Regardless of what I plugged them into, the U12Ts sounded great.

Overall Sound Impressions and Frequency Response: The U12Ts present with a decidedly U-shaped frequency response. They have a strong subbass and upper treble emphasis, as well as a warm-neutral midrange with a slight, tasteful bump in the lower mids that add a nice hint of body and fullness to the sound. The upper mids are a little pulled back, which recedes some vocals in that range, but it’s in no way egregious and imparts some (perhaps slightly manufactured) staging depth.

Just to reveal my biases, this tuning very much aligns with my preferences. There’s a smoothness and fluidity apparent throughout all frequency ranges, without sounding muted or blunted in any way. In fact, the U12Ts pack a surprising amount of punch and impact, which for some reason I was not expecting. Overall, they’re just a very musical IEM, combining an easygoing tuning with excellent technicalities and dynamic range. Let’s delve a little further into the weeds.

Bass: The first time I put these things in my ears I actually felt they were almost too bassy. As my ears adjusted, the beauty of the U12Ts bass response made itself readily apparent. This is not just excellent bass “for a balanced armature driver.” This is just plain excellent bass full-stop. It actually possesses many of the qualities of a dynamic driver, with a lengthier decay, fantastic extension, and really good textural nuance. Yet it still maintains some of that desirable agility that BA bass can have. It even hits pretty damn hard when called upon. I was very pleasantly surprised with how satisfying certain bass focused tracks could be.

In general, the added subbass presence here contributed nicely to a lot of the music I listen to – jazz, funk, neo-soul, Snarky Puppy (<3), R&B, EDM, French-house, some rock, a little classical (mostly string quartets). It achieved really good solidity and body while demonstrating exceptional control. I was also incredibly pleased with the bass detail and clarity. No matter what genre of music I was listening to, fast bass passages were expertly navigated and came through with transparency even during the most hectic musical moments. Some high-quality DDs can provide a little better density and deeper feeling rumbles, but I can’t stress enough how fantastic this bass response is overall. 9.5/10

The mids on the U12Ts are excellent. There’s a very slight lower mid emphasis that adds just the right amount of warmth and richness without ever sacrificing clarity. In fact, the resolution is absolutely insane, and remains truly impressive after over a month of daily use. There’s a smooth, but pristine quality to everything. It’s warm, but never smeared, congested or thick - just laid back and ultra-clean. I absolutely love this tuning, as it permits for a very easygoing listening experience with zero harshness, grain, or haze. This also makes the U12Ts pretty damn forgiving, even on poorly recorded tracks.

The midrange timbre of the U12Ts is highly realistic and emotive. Obviously, the excellent technical aspects contribute greatly to the ability to present an accurate rendition of instruments and vocals in this range. However, there’s also a nice roundedness to everything that provides the mids with an extra lifelike quality. Vocals sound very natural with added depth and richness; guitars sound plucky and beautifully reverby; and brass instruments sound breathy, punchy and lively. Though the U12Ts do not display the same textural qualities that were apparent with the Unique Melody MEST (mk1), it does have a more agreeable tuning in this range overall than the MEST, and presents with a bit more detail, but more on comparisons later.

Now, it’s important to note that there are some characteristics within this range that may not entirely align with everyone’s preferences. Vocals are not quite as present and feel a bit more pulled back within the mix when compared with other sets. There’s also a pretty noticeable dip in the mid-range from 3-4k, which takes some of the spice off the leading edge of percussive hits. While this generally lends favorably to the fatigue-free listening experience, I sometimes like a bit of spice here and there.. Overall though, phenomenal detail retrieval plus extremely natural timbre equals a top-tier midrange presentation. 9/10

All this and I haven’t even gotten to my favorite part of the U12Ts frequency response – the treble. I did warn you that this would be a bit of a shill review, but I just can’t help but love the treble response here. It’s very unique actually. It’s got superb nuance and distinction from the other frequency ranges and comes off as highly refined. Not only that, but there’s a ton of air above 10k which just gives everything in the range a sparkly wonderful burst of clarity (pretty sure that’s the technical term for it) no matter what you’re listening to. The whole range sounds undeniably smooth and agreeable, while also being well-extended without any noticeable roll off.

The detail in this range is just amazingly good. In fact, it’s probably the most detailed treble response I’ve heard to date on an IEM. Everything feels expertly delineated and nuanced. Cymbal strikes exhibit a noticeable variety based on where exactly the drummer is actually making impact; and tiny blips and upper frequency noises come through with fantastic presence and vibrancy. There’s also a bit of extra decay and reverb that’s just so musical and timbrally satisfying. Now, would I call it perfectly "natural" or "neutral"? Probably not. There’s absolutely some coloration going on here, but it’s all for the better. On top of the wonderful tuning characteristics, the treble has real body and fullness - none of the wispiness that one might expect out of a warmer, smoother overall signature.

All in all, the U12Ts treble manages to be thoroughly non-offensive, while also being beautifully airy and ultra-clean. Really best in class in my opinion. 10/10

Soundstage and Imaging:
Speaking of best in class, the soundstage and imaging here is also done at a top-tier level. Regarding the soundstage, the U12Ts have a special dispersed, open feeling presentation. This is accomplished with fantastic width and depth, in conjunction with super precise instrument placement. The imaging here never feels like it’s jumping around. If something is moving from left to right, you can hear every single moment along that directional spectrum. When blended with the U12Ts openness, this really becomes more similar to a headphone-like presentation than that of an IEM. This character is helped along by the phenomenal detail retrieval and ability to vividly display all the tonal elements of each individual note.

I can’t stress enough how fun and musical this staging presentation ends up being. It’s really one of a kind and in many ways could be considered the crowning achievement of this IEM. The one thing I’ll say is that there’s not as much of a “3D” effect that some IEMs can portray, since there’s a slight lack of textural feel. Also, it can get quite diffuse feeling and, in combination with the slightly pulled back mids, the U12Ts can come off not as intimate as some may like. Overall though, in terms of pure enjoyment factor, the staging and imaging here are substantially better than pretty much everything I’ve heard in the IEM space. 9.5/10


U12T vs. UM MEST (mk1)
: This is a close one. I absolutely loved the MEST (mk1) and still think they offer a very unique, satisfying, highly textural sound experience that is hard to beat – particularly for the price. That said, I do prefer the U12Ts by a decent margin. Though the U12Ts don’t have the same textural feel throughout all frequency ranges that the MEST has, the U12T’s tuning is a bit more agreeable to my ears. The MEST (mk1) are pretty V shaped with a forward vocal presentation, and I’d say a bit more treble focus than the U12T. Whereas the U12T have a smoother, more laid-back U signature with emphasis on opposite ends of the frequency spectrum. I find that the U12Ts tuning presents with a bit more coherence and ease while not sacrificing any technical aspects, whereas the MEST sometimes feels like it's trying hard to impress.

To be more specific, though the MEST (mk1) have slightly more bass texture than the U12T, the added subbass presence on the U12T was more satisfying for me overall, and I felt that the agility and technical nuance of the U12T’s bass was more than enough to compete with the MEST’s fantastic bass response. As far as the midrange, I do prefer the tuning of the U12T as it just feels more linear and even overall, with a nice bit of added warmth that I found was a little lacking on the MEST. I also felt that the U12Ts provided a noticeable jump in detail retrieval when compared with the MEST, though the MEST is still a high-level technical performer. Treble is where the U12Ts kind of separate themselves from the MEST for me. I just love how smooth and airy it is, whereas the MEST kind of presents treble in a more exaggerated up-front manner. Not to say the MEST is harsh by any means, it just feels slightly less refined than the U12Ts.

The one thing that the MEST has over the U12T is a bit more of a “3D” staging effect due to a more textural overall presentation. This aspect of the MEST is still very unique for me and provides a tactility that is super addicting. My main issue with the MEST, however, was how fit dependent it was, which made daily use a bit more finnicky than I wanted it to be.

Overall, I do prefer the tuning and the technicalities of the U12Ts, but it’s really not by a lot. The MEST is still a fantastic IEM and considering that it can often be found for a considerably cheaper price than the U12Ts, it’s a pretty close call. However, in my view, the U12Ts win this head-to-head when all is said and done.

U12T vs. Sony IER M9: This was not as much of a contest in my view. While these two IEMs share some similarities in their presentation and tuning, the M9s do everything just a little worse than the U12Ts. The bass on the M9s is a little bloatier, more mid-bass focused and less textured than the U12Ts, though it’s still excellent as far as BA bass performers go. The mids between the two are a little closer, as the M9 has great timbre and tonal balance. However, the U12Ts just have an extra bit of dynamic punch and musicality in the midrange that is a little lacking on the M9s. The U12Ts also do treble noticeably better than the M9s, with the M9s coming off as a bit darker overall, with less clarity and air. This is saying something as the M9s are by no means a dark IEM and have very good extension, it’s just no match for the U12Ts top-end transparency and refinement. The staging is where the gap between the two IEMs gets a little wider, both literally and figuratively. The M9s sound a bit claustrophobic when compared with the U12Ts, despite their otherwise great imaging and separation capabilities. The U12Ts are far more open and spacious feeling, with much better depth characteristics. I'd take the U12Ts every time, but the M9s still offer great price to performance.

U12Ts vs. ThieAudio Clairvoyance: The Clairs are quite a nice IEM, presenting with an agreeable tuning and great technical abilities for the $700 price tag. That being said, they don’t really compete with the U12Ts, which is somewhat to be expected. Though it’s maybe an unfair comparison, I did want to say that even though the Clairs have a dynamic driver for the bass, I actually much preferred the bass response on the U12Ts. The amount of extra detail and texture you get from an upright bass pluck on the U12Ts is on a much higher level from the Clairs, which sounded a bit one note in comparison. The mids on the U12Ts had a much nicer timbre and that nice added low-mid body that was not as present on the Clairs, though I will say that the Clairs have a really nice evenness through the midrange that just felt right with certain vocals. The treble is no contest really. I did not love the treble on the Clairs at the end of the day as it felt a little bit wimpy and grainy, despite being pretty detailed. However, I did find that the soundstage of the Clairs compared favorably with the U12Ts.

Not surprisingly, the U12Ts are a noticeable upgrade from the Clairs, and in this case if you’re deciding between the two, I’d save up some money and try to get a good deal on the U12Ts if you can. They’re just so damn good.
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little grayman
Realy nice review.
It's 2024 and the u12t are still awesome iem


Reviewer at Headphones.com
Pros: - excellent bass response (for a BA)
- slick, resolving signature and superb technicalities
- plays well with most genres
Cons: - no particular standout
- lackluster accessories
For the best viewing experience, please view on my site here.


Anyone who’s based in the US knows the struggle of demoing high-end IEMs - or even IEMs in general - and my experience bears no exception. In fact, it was only by a stroke of luck that I got to listen to the U12t: I was doing a local transaction for another pair of IEMs, and the seller happened to own the U12t so he let me have a listen.

With the ongoing pandemic, my first listening session with the U12t basically took place in my car with the seller parked next to me. Certainly far from ideal, but in the first couple minutes I listened to the U12t, I was hooked. And I’m not exaggerating when I say that for just a moment I forgot I had IEMs on. So when the same seller put them up for sale a couple weeks later, well, I had to cop them. While my initial hype has abated, make no mistake that the U12t are endgame-worthy IEMs. Let’s talk about why.
The Tangibles

The U12t comes in a large, cardboard box. Accessories include various tips, a hard-plastic case, M15/M20 Apex modules, a clip, and cleaning tool. It certainly doesn’t feel like you just bought $2000 IEMs, and the spelling error on the packaging is just the icing on the cake.



"caused my miniature speakers" under Apex. Oh dear.

Build quality of the IEMs is good. I bought mine second hand, so I’ll refrain from commenting too much here. However, a clear weak point of the IEMs is the lack of a recession point for the cable pin. The left side on my U12t experienced audio cutout when the pin wiggled and had to be sent in for warranty.



The cable looks and feels good...but falls short because of the memory wire. I’m guessing it’s useful if you’re actually using the U12t on-stage. But from a practical standpoint the stuff is a nightmare. It exacerbates the strain on the pin connector point, and makes it one hell of a hassle getting the U12t into its case.


As for the case, I actually rather like it. Sure, it doesn’t look fancy, but I’ll take function over form any day. And unlike a lot of other cases, it’ll actually protect your IEMs and it holds all the accessories you could need for the U12t.

Fit, Isolation, and Comfort

Now that I’ve finished making fun of the U12t’s janky packaging and accessories, it’s mostly uphill from here. Because frankly, it doesn’t matter how good the sound of an IEM is if you can’t wear it comfortably.

To this effect, the U12t are the most comfortable IEMs I’ve used; I attribute this to a couple factors. First, the shell is nothing special. It’s of a standard size and doesn’t try to penetrate the confines of your ear like some other IEMs do. And second, 64audio’s Apex (air pressure exchange) technology really works. I don’t get that annoying build-up of pressure like I do with my other IEMs. In tandem, the simple shell ergonomics and Apex tech make the U12t something that I could listen to literally all day.


As always, fit is 100% subjective. But definitely give these a shot if you can’t stand that ticking, time-bomb feeling of pressure building up in your eardrums.

Sound Analysis

Testing Methodology:
  • FLAC files off of a Shanling M0. I swapped the tips and cable, but with no discernible difference in sound.
  • My genres of preference include country, film scores, instrumentals, EDM, and pop.
  • Burn-in - Don’t really believe in it, unless we’re talking about your brain and ears getting used to the sound. I am the second or third owner, so I’d imagine that they have well over a hundred hours on them at this point.
  • The U12t requires minimal power to drive. There’s no hissing with any of my sources. I also don’t listen any louder than 75dB, so all you head-bangers take that for what you will.
Bass: BAs are known for their speed and detail, but they often lack the authority of a traditional DD. Luckily, this isn’t the case with the U12t: It has exceptional bass for a full-BA setup. The U12t's bass is more textured, nuanced, than a good deal of dynamic driver IEMs I've heard. Plus that natural decay; I don't think I've heard any other BA IEM that can match the U12t's response here. It's not perfect of course: There's a general lack of density to its notes (plasticky-ness), and the deepest registers of dynamic slam are notably absent. But it sets the bar impossibly high for most any other BA IEM I've heard, sans perhaps the Sony IER-M9, and it's enough to sate even my admittedly strong taste for bass. Oh yeah, quantity with the M15 module is a bit lacking for my preferences. More balanced, certainly, but the M20 module slaps on a small sub-bass shelf which adds that extra "oomph" I'm looking for.

Mids: The U12t doesn’t play favorites here like some other IEMs. Both female and male vocals are smooth and dead-balanced in terms of note-weight; this results in an extremely safe midrange presentation. Notably, there is a dip to the upper-midrange, from ~3-5kHz, which serves to position vocals further back on the stage. When you listen to the U12t, you're more of an observer - watching it all unfold in front of you - rather than in the mix itself. This does wonders for the extent to which the U12t is able to project the center image, and it begets an unprecedented sense of depth.

Highs: The U12t makes use of the Tia (tubeless driver) for the highs. If I could sum up the treble response in a few words: Detailed and unique. The mid-treble has something of a dip from 8-10kHz before spiking again in the highest registers around 16kHz. What this results in, to my ears, is a more laidback treble response that has excellent detail and air at the top. Still, it's not at all accurate relative to real-life instruments, and if you can't hear that high up in the frequency range, the U12t will sound rolled-off and lacking extension.

Overall, the U12t has a coherent, slick presentation. This is largely in due to the transient smoothing that the 64 Audio BA drivers all seem to exhibit. Speed itself is fast - more than enough to make the Andro 2020 (an IEM I'd consider fairly quick) sound slow while A/Bing. Still, the transients take something of a blunted, round edge - particularly in the bass and midrange as I noted earlier - and as a result, the U12t lacks a certain crispness to its notes. This does play into the U12t's coherency, as there's a pleasant "mellowness" to its presentation that compliments the mid treble dip. It’s not quite a laid back sound, and yet I find that I can listen without fatigue for hours on end.

Let’s talk about technicalities because the U12t plays ball here too. As I just touched upon, resolution does take a small hit because of the tone. Despite this, the U12t is still incredibly resolving, and for sheer detail retrieval - not to be confused with resolution - it more than holds its own. Something special about the U12t is the timbre; it is extremely clean, more so than any other BA setup I've heard. Imaging is also terrific in terms of positional-cues and center image diffusal, while not quite meriting the oft-misused term “holographic”.

Something that doesn’t get talked about enough are the U12t’s macrodynamics, the extent to which an IEM is able to scale quiet-to-loud sections of tracks. Indeed, most full-BA setups are plagued by “compression” in which they sound, for lack of a better word, flat. But the U12t excels with expansive, dynamic contrast and quick transitions; I’ve not heard another BA IEM that can match it in this respect.

The Verdict

When I first saw the U12t online, I balked at the price. Just the fact that such expensive IEMs existed blew my mind. But also, who in their right mind would spend $2000 on a pair of IEMs? I think you can guess who (mostly) ate their own words and fell down the rabbit hole.

Let’s talk about value. This is where things get murky because I haven’t actually heard any other flagship IEMs yet. Devoid of this fact, do I think the U12t are worth $2000? Some people will hate me for saying this, but to be blunt - not really. I certainly wouldn’t pay that much (I paid closer to half), and I think even most audiophiles would struggle to justify the price. Of course, this sentiment is applicable to most audio gear in general, as the end rarely justifies the means. So the only time I think something like this can be truly called “worth it” is if it’s your endgame.

This begs the question, who is the U12t for? As someone once infamously said: The U12t is not special. It’s that kid in school that gets 90% on every subject, but can’t seem to get a perfect score in anything. If there’s a specific aspect of the frequency range or of technicalities you’re partial to, then there’s better options. The more I’ve listened to the U12t, the more I’ve realized that there’s no single standout for me. But this is also why the U12t is probably the safest flagship IEM you can buy; it simply plays well with everything. It’s an exercise in when the whole is greater than the sum of its parts, and most would agree that’s a sort of special in itself.

Score: 8.5/10
Understanding my scoring: This is a personal, subjective assessment of an IEM’s sound quality. I don’t take into account any other factors, and it's relative to the absolute best sound I've heard. Take it with a grain of salt! I’m not going to lie; I have high standards. But I’m not telling anybody how they should hear something – it’s a reflection of what of me, myself, and I hear.

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I’m sure there are variants out there in the U12T. I’ve seen everything from it being boring to it being overhyped or just plan bad. Having gotten my first pair finally, I can tell you without a doubt this is my favorite IEM. I have engaging, powerful, and yet holographic imaging and laser like treble without ever being too harsh. Mids are perfect and that bass on this All Ba breaks the laws of physics. My U12T is a flat out work of art and performance unlike anything over experience in my life.
I agree. The first U12t (New logo 2021 with more rounded silver trim) that I had, sounds worse than the current U12t (New logo 2023 with more boxy/flat look around silver trim) that I own right now. The first U12t that I owned, had worse technicalities & the high treble peak was just too much for me... The current U12t that I have, has less upper treble peak, slightly more mid-treble, slightly less mid-bass, slightly leaner lower mids, & also sounds more technical as well. Note : Stock silicone tips & the LG V40 were used on both the U12t's.
The u12t is already a legendary earphones like an Andromeda, just in a different price category


500+ Head-Fier
Pros: exceptional bass (effortless in speed, precision, balance), impressive treble with both sparkle and body, overall balance, helpful customer support
Cons: midrange is not tonally perfect but close, cable feels cheap, a bit large / heavy
It’s a bit hard for me to write this review, but I find it necessary — the 64 Audio U12t has been a major factor in my unexpectedly low level of enthusiasm in audio gear… but maybe not in the way you’d expect. Scroll down to Conclusion for a TL;DR.

It was a summer day in the streets of Los Angeles, where I found myself half lost looking for the entrance to CanJam Socal 2018. After buying and trying many IEMs over the prior two years, I had settled on the Campfire Andromeda as my personal portable audio paradise. Regardless, there were so many IEMs out there that I haven’t had the pleasure of trying. I was excited to change that on this day.

Two hours later, I was both a bit disappointed and relieved to find that every IEM I tried in the venue felt a bit underwhelming. With most of them, I caught myself thinking, “Meh, I prefer my Andromeda”. But of course, there were some standout exceptions that had me second guessing whether or not I was ready to settle — namely, the 64 Audio U12t. This IEM clearly stood out to me and managed to solidify its place in my mind, surpassing my beloved Andromeda in every single aspect I could imagine. And that was that.


2 years later, having gone through several different revisions and colorways of the Andromeda, I’ve finally reunited with what I feel is a long lost friend. The U12t retails for a hefty $1,999 USD direct from 64 Audio. As its name suggests, each housing sports a 12-driver setup featuring their proprietary tia drivers and standard detachable 2-pin 0.78mm interface.


The unboxing experience is professional and straight to the point; it’s not the most premium packaging I’ve ever seen, but very well organized and concise without seeming like an afterthought. You are greeted by a very well-designed protective carrying case, a variety of eartips, the U12t IEMs, and stock cable all neatly fitted into a dense foam cutout. Inside the carrying case you have access to alternative apex modules, a shirt clip, and a cleaning tool.


Build quality feels like it wouldn’t be an issue — the housings are machined to a smooth anodized aluminum finish; you can see slight inconsistencies in the texture but nothing visible from further than 6 inches. Coloring is consistent around the shell, with reasonably sharp L/R indicators on the inside face of the shell along with the unit’s serial number. They’re also a bit hefty and large, so those who have small ears or those who commonly find issues with IEM weight may be turned away from the U12t.

One thing to note is that the included cable feels a bit out of place for a $2000 product. It's a bit stiff and jumpy, doesn't look premium at all, and overall feels a bit awkward with its matte, 'papery' texture. That being said, those willing to drop this cash on an IEM probably wouldn't mind picking up a boutique premium cable either -- lots of good, affordable options out there nowadays!


Something I noticed is that the mesh filters are held in the nozzle by a strip of adhesive; I’m not sure what would cause this to deteriorate but I had an issue where the mesh was pushed inwards while using the included cleaning tool to remove some wax. I’d like to give 64 Audio’s support team a massive shoutout for helping me to resolve my case with nozzle filter, and making the warranty process absolutely seamless. You couldn’t imagine the look on my face when I realized that I had broken the nozzle of these expensive IEMs, so that was a massive sigh of relief.


The Apex modules have two notches cut into the sides to simplify removal. These can sometimes prove to be a bit tight, more commonly so in the carrying case than the IEMs themselves. I’d recommend taking it slow, as the edges of the module can work their way under your fingernails if you aren’t careful. They slide snugly into the module slots in the IEM with absolutely no room to spare, ensuring a secure fit without any rattling or play. The U12t comes stocked with a pair of M15 modules and a pair of M20 modules; the former in silver and the latter in a gunmetal shade.


In terms of sound, I’d consider the U12t to be an excellent all-rounder — it’s got exceptional bass response that reaches down effortlessly to the lowest of lows, ample-bodied midrange with solid note thickness / clarity, and a clear treble performance that feels both precise and full. Bass is built with an emphasis on subbass, lifted generously in the lower region without being weak in the midbass. Midrange is bumped up in the upper-midrange, but can occasionally sound a tad muffled in the very highest vocal registers with certain vocalists. Treble is full-bodied throughout with great presence, though it may lean towards what some may consider bright. Resolution is great throughout the spectrum, really demonstrating its technical prowess on any well-mixed track.



Bass, as mentioned, rumbles effortlessly at the lowest of my hearing range. To note, this bass presentation is super tight and textured; not a single beat is missed here. That being said, it doesn’t seem to have the visceral ‘eardrum pounding’ subbass that comes from some basshead dynamic driver earphones I’ve heard. However, don’t get me wrong — the U12t’s bass is no slouch, it’s tuned well above normal and slams hard when called for it. It’s hard for me to put into words, but the U12t’s bass feels very effortless. It’s as if the U12t can do what it’s expected to without a hint of sluggishness or err, hyper responsive and capable in its performance.


Midrange tends to be a very touchy region for most people — some like their vocals to be crisp and sharp, while some prefer a thick and rich vocal tone. From what I’m hearing, the U12t sits just slightly closer towards the former, lending a very clean and distinct tone that puts out note resolution and detail with confidence. Lower midrange is never bloated or muddy (something that eventually made me give up on Andromeda), and center midrange comes off with a nice weight that I’d consider just a very slight touch short of perfect. Vocals, while mostly natural, may lack a bit of high upper-midrange flexibility; they can occasionally sound constricted or ‘limited’ in the sense that the vocalist’s full note isn’t given 100% room to resonate or interact with the room. It’s close, but just not completely there. However, for most listeners (including myself), it’s very easy to see past this and enjoy the overall sound of the headphone for its other very strong qualities.


At one point, I considered myself to be somewhat of a treble-head (quality, not quantity!). Mostly due to being a huge fan of the Andromeda, and taking a particular liking to the high-end sparkle of that tuning. That being said, the treble on the U12t is incredible — it’s taken me quite a few IEMs to find one that I flat out preferred over the Andromeda, but this is without a doubt the number one contender. The treble is super crisp and resolving, and has a wide sense of openness and staging that still feels natural. Lower treble is also well-bodied and has a good amount of crunch, avoiding the overly aggressive or harsh brightness that is present with many other attempts at reproducing that elusive “sparkle”. Not once does the U12t sound muted, dull, or lacking in treble extension. I’d say that the treble performance is one of the U12t’s greatest qualities, just as impressive as its bass region with its sheer effortlessness and precision.

A Bittersweet Conclusion

I know it may sound cliche at this point, but the U12t has decidedly become my ‘endgame’ portable audio choice. I no longer find myself scouring the classifieds and second-hand market for my next potential earphone, spending countless hours on the web browsing the latest audio trends. It’s a little bittersweet, but in hindsight it marks a very significant milestone in my audio journey; the U12t along with the HD800 has left me with a sense of satisfaction in my setup, relieving me of the once-rampant audio bug. I finally feel content with both my portable and desktop setup, finally shifting my priorities to focus on enjoying the music rather than the equipment.

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@ustinj Yea, multi-BAs are more likely to be "all-rounders". Also, you won't get that unpopular driver flex :)
Hi, just re-read your description of the modules and I think you may have mixed it up. The M20 is silver, the M15 is gunmetal grey. You can check the 64A website to confirm. Hope you're listening with the right modules :) (I prefer the extra bass response of the M20 myself).
John Massaria
John Massaria
$2K is way too much for less than perfection- pass...
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500+ Head-Fier
Trying to get a pair of these next - auditioned next to Solaris and went with those, but was wondering at the time if the U12T could have been the more long term solution!


New Head-Fier
Amount of bass was satisfying and well controlled, but detail of sub-bass was disappointing, compared to the Legend X.
Everything about imaging and mid-low&mid&high resolution was perfect. Just perfect.