64 Audio U18 Tzar

General Information

18 Driver co-flagship IEM from 64 Audio. Just to clarify, that is 18 drivers PER SIDE! That's 36 drivers in total!!!
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Pros: Insane technicality, especially detail retrieval
Ultimate reference monitor
Excells at just about everything
Extremely adaptable
Honestly, everything about it
Still very relevant years after release
Cons: Pretty high build time
As there's tons of reviews of the A18t out and about, I will keep this brief as more of a contribution than a full review


2019 has been a pretty crazy year for audio. So much new tech, drivers, configuration, hybrids, tribrids and whatnot. Madness galore.

To answer the question in the title quickly - yes, the A18t absolutely stands its ground years after its release and remains one of the most competitive monitors on the high end market. There's a couple of features that in my opinion give it a certain legendary status, that would make it relevant now, in 5 or 50 years:

1. The BA IEM that ended the BA driver count war. I know more drivers doesn't equal better sound, but how brutally cool is it that an IEM has 18 drivers per side?! It's even better than in this case, more drivers does get you better sound though


2. Detail retrieval. Almost no other IEM I have tried is able to deliver that much detail. The A18t will give you every single note and nuance of a recording. While that may not be an absolute requirement for an enjoyable listen, it will most certainly make sure that you never get tired or bored of it. No matter how long you've had it, it will continue to impress you listen after listen

3. Scalability and responsiveness. The A18t's sound signature and technicality is extremely responsive to cable and source rolling - as source and cable tech keeps improving, so will your A18t. Makes for an extremely exciting product to own, and any time you might get tired of it, you can simply change something in the setup and it will be as good as new. Not only that, but the APEX modules further enhance that experience, giving you even more possibilities to adapt the sound to your moods or preferences.


5. APEX pressure venting. That's something I didn't appreciate until I was on a place and my earphones didn't make my eardrums feel like they're blowing up. Also gets you a completely fatigue-free listening, which is most certainly a blessing.

6. 64Audio - you're buying from one of the most consistent and reputable companies out there. You're sure to receive the support you need at any and every step in the future


7. Stellar performer, capable of acing anything you throw at it - the A18t has no pronounced weakness, or any specific genre that it can't perform on point. It is sometimes too revealing of any recording flaws, but that isn't its fault - blame the artist.
The number of drivers war has end now :) less is more.
@IgeNeLL I agree, especially with all this new driver tech being incorporated. The A18t was absolutely groundbreaking for its time and it remains one of those legendary IEMs
Good read, even better housing design :)
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64Audio U18 Tzar vs 3 other IEMS (Noble Katana, Campfire Andromeda & Sennheiser IE800S


About my disclaimer...The four IEMs in this article were bought by me and I have no bias to any particular manufacturer. Irrespective of whether I was sent them free in return for my honest opinion or paid for them myself what you will get will be my honest opinion.

About my opinion...Everyone has different biology including ear canal acoustics and brain burn. We have all had different audiophile careers, genre preferences and will have become accustomed to a different 'house' sound over time. We also all have differing frequencies responses as well as variations between left and right ears in some frequency areas. We will have drawn conclusions about what we consider ‘reference’ based on many factors and those can also differ. It’s for these reasons that my article is merely my own opinion and will differ from others.

About my Audiophile career...I’ve been evaluating Hi-Fi equipment since the 1990's (Speakers, amps, headphones, tape decks, turntables etc) extolling the virtues of one over the other and identifying the nuances that set them apart. Later in the early 2000s I focused more on personal Hi-Fi equipment and was deep into IEM's for the appeal of having one’s own private performance delivered directly to ones ears to the exclusion of any other sounds.

About the IEM’s selected for comparison...I explored many IEM’s and shortlisted four I liked for the purposes of this evaluation as a means of comparison. They are by no means the only considerations and there are many others I am hoping to evaluate. Most differences at this level come down to personal preferences, the shell shape and design, the quality of manufacture and the materials used and supplied cable and accessories, R & D, driver count and tuning rather than absolute audiophile dominance. The main differences will come down to individual sound signature preferences. Recommendations should not be taken too seriously. Items classified as top tier, sometimes become so due to the reviewers personal preferences or by the excitement of new ownership & brand loyalty.

About EQing... We want IEMs to sound correct out of the box. Applying EQ negates the point of travelling on the audiophile journey to seek the equipment that most perfectly reproduces sound without the need for any kind of manipulation. I’m ok with selective EQ when done as part of the digital conversion phase. This kind of EQ can be achieved if the source has a biometric EQ built into the player, or if the DAC has an integrated EQ (Such as the Shure SHA900 or the Audeze Cipher cable). Perceived differences between articulation, imagery, depth, air and detail can be more closely matched between IEM's by applying gentle EQ in the right places. This lays bare the true differences between the IEMs. At times during this evaluation I’ve applied EQ to understand better any differences in overall timing, layering and articulation.

About cables and DACs...In order to maintain a consistent set of results I have stuck with the same DAC the Shure SHA900 and sometimes the Dragonfly Red as a crosscheck. I briefly tried the Apple Lightning to 3.5mm earphone adapter cable, and the similar Moshi Integra cable enjoying good results with those with a slight preference for the Moshi. All the IEM’s have been evaluated using the bundled cables.

About my source material...All evaluations are done using a wide range of musical genres including Rock, Pop, Jazz, Electronic and Classical. There is a big emphasis on Soundtrack and Classical since I find these genres the easiest to pick out attributes of the IEM. Over the years I have earmarked a selection of tracks for testing Hi-Fi equipment some of which will push them to the limits. All music is evaluated in a lossless format and nearly all tracks are 44.100khz 16 bit.

About the U18t’s (build and packaging)...The U18t’s are well packaged and come complete with a protective composite case which also serves to neatly store the M20 and M15 Apex modules and cleaning tools. Upon un-boxing the U18t’s for the first time it was a bit of a struggle to grip the earpieces and remove them from the foam packaging material as they were flush with the surface gripping it tightly, with the foam too thick to push from underneath. There is a selection of tips to choose from, none of which I tried as I have a huge selection of tips accumulated over years and I have come to know what works best for me. The earpieces themselves are exquisitely designed, beautifully rounded for comfort and consistent with a product at this price point. It is difficult to see how they could be improved. The supplied cable is nearly perfect. It has a robust braiding in the main section which cannot be unravelled by twisting. The left/right side split section has normal twisting but the quality and rigidity is about perfect to give the sense it is unlikely to easily unravel. The cable adjuster feels reassuringly tight such that you can ‘set and forget’ it. There is a very rigid cable memory section which wraps around the ear like a pair of glasses you forget you’re wearing and the 2 pin connector terminates around a very rigid fixed plastic section which is about the right size and shape to neatly wrap around the ears. I feel the 3.5mm right angled connector whilst of a high quality is unnecessarily heavy for a cable of this type and looking at the U18t’s version 1 cable the 3.5mm connector seems less weighty. Cable microphonics is kept to a minimum for this type of cable. Overall I prefer the V2 cable for its overall build and consider it amongst the best I’ve yet seen supplied with an IEM. When the memory cable is positioned correctly, the inner metal of the earpieces rest neatly on the ear. There is a slight protrusion of the front of the earpieces and the Apex modules. Generally they are comfortable for extended listening and my preferred tips were de-cored Shure Olives over Comply cores.

About the M20 & M15 Apex modules...The included M20 & M15 Apex modules add an additional flexibility allowing you to slightly fine tune the sound. 64Audio explains that different levels of isolation are achieved using the different modules. I have also understood that the Apex modules are designed to reduce fatigue and pressure build-up over extended listening. I have noted that the Apex modules do indeed work as advertised however they will not change the overall character of the IEM’s but rather fine tune them. After experimentation I stuck with the M15 module for this evaluation preferring its attenuated bass response.

So what about the sound ? (First impressions)... First impressions are that they produce a detailed, airy, analytical and fast sound leaving nothing vague or uncertain in their presentation, the bass is tight and well extended to the sub bass where it has amongst the most convincing of full bodied presentations a little north of neutral. There is an abundance of sparkle also north of neutral, the imagery enables precise placement of instruments and sound effects both horizontally and vertically in the expansive soundstage with sounds seeming to just ‘pop’ into being in a remarkably magical way. The U18t’s are uncompromising with high frequency detail and seem to emphasise the overall tuning of a recording whether bright, neutral or dark. Immediately you are able to identify every nuance together with the studio or concert hall acoustics. Occasionally some tracks sound sparkly & thin with less emphasis on the mid-highs and more in the upper-highs. Rarely notes with very high frequency harmonics can have slightly bright sounding edges. There is an abundance of texture and detail, the well extended dynamic range pushing deep into the highest frequencies and beyond providing unprecedented air and shaping, particularly in acoustics and harmonics that is rarely experienced in an IEM. There is a very real sense of feeling the instruments such as strings, kick drums and canastas. The U18t’s take the music, strip and lay bare every nuance of detail that can be extracted. The mid range doesn’t seem to be lacking either; vocals are detailed but not thin sounding but not quite neutral either being slightly warmer but still with bright edging. Sibilance is there where expected and there has been no shaping to attenuate this in its presentation. Strings and brass are richly detailed and at times harsh and uncompromising. Layering is about perfect with everything sounding orderly and correct with even the most demanding of passages.

So what about the Apex modules...? Comparing the sound profiles of the 2 modules I found the M20’s to have more sub-bass, bass and low-mid response, with slightly attenuated responses at the treble end upwards from 11.5k. Overall I found the effect more distinct at the low end, whereas the changes at the high end were more subtle. The M20 module reduces slightly the sense of air without altering the overall character of the signature. Overall I preferred the M15 as it sounded a little more balanced with its more restrained low end but subtle effect on the highs, counter intuitively bringing out the mids a little more.

So what about after extended listening...? It takes a little time to adjust to the deeply focused and analytical U18t’s when compared to some of the more ‘relaxed’ sounding IEM’s. It’s worth it because once the ‘Brain Burn’ is complete you are left with such a transparent and lifelike presentation that you can forget sometimes you are actually listening to IEM’s. You are rewarded with a totally immersive, engaging, visceral and lifelike experience. Imagery is stepped up a level, speed, detail and soundstage, all present in abundance, thinness and brightness at times still there but more distant, with only the occasionally harshness still apparent in strings and horns in some recordings but giving every sound a clear edge and texture.

So whats going on here...? The sub & lower bass are a little emphasised, the lower-mids are presented fairly neutrally, in the highs there is no compromise or trade-off around the 5-7khz to control sibilance where there may even be some slight intensity. Some slight attenuation from 8.5k until 11k possibly accounting for the occasional sense of ‘thinness’. From there upwards it seems there is notably less drop-off than any of the other IEMs upwards towards 15k and into the ultrasonic range which accounts for the abundance of ‘air’ but also the slight tizziness in some tracks on high-hats, cymbals and brass for example. This may be the trade-off required to achieve this kind of shaping and transparency.

So are they Neutral...? Not far off; when comparing the presentation of the U18t’s to the other IEMs and also to room speakers, I found them closer in overall balance of bass, mids and highs than several other IEMs and also closer in overall character to floor-standers and open backed headphones like Grados. In overall balance they give some perception of neutral, however I found them to be a little sub-bass to low-mid emphasised, a little mid-high recessed and a little high-high emphasised. Overall a most compelling tuning providing some added weight, warmth and sparkle but leaning towards neutral/mainstream hybrid rather than studio reference.

About the U18t’s (Overall)...64Audio have shoe-horned 18 drivers into each earpiece configured as 8 low, 8 mid, 1 high-mid and 1 ‘tia’ high, a fine feat of engineering. Like a sports car manufacturer incorporating more cylinders and cubic capacity to achieve more power and refinement. If you are the owner of such a vehicle you may not be using all the power all the time, but it’s nice to know its available when called on. But how does this translate to the U18t’s in providing a smoother cleaner more articulate sound? Well not at all really since one is an engine the other is an IEM! But the U18t’s do indeed manage sub-bass impeccably and have perfect timing and articulation with their 8 bass drivers in each earpiece. There are no issues with the mids either, sounding natural and perfectly articulate. The high-mid and tia drivers also seem to be extracting plenty of detail and even more sparkle. It is difficult to imagine how they could be improved whilst still retaining their very compelling tuning but I do find some tracks sounding a little bright and tizzy, and at times even with the M15 modules the bass can be a little hot. This surely is a symptom of this level of detail and focus that is bringing out both the best and the worst in those recordings and could be what is making them sound to me amongst the most exciting and addictive IEM’s yet. Mostly I love them for their staggering and life-like presentation with the impeccably clean bass, clean mids, airy highs and expansive soundstage. They are absolutely top tier IEMs and they have a richness of sound and refinement to match.

Defining words: Airy, grand, articulate, wide, detailed, fast, analytical, razor sharp, transparent, complete.

So what about the Campfire Andromeda’s? One needs to be very cautious when switching to these after extended listening to the U18t’s as the immediate impression may be one of slightly veiled highs but more rounded mids. This would be a mistake as when identifying differences by doing A/B tests any differences will be exaggerated as ones brain is identifying the differences between the IEM’s rather than an accurate ‘reference’. It is best to give plenty of time to adjust to the different sound signature before evaluating.

General impressions are of an extremely balanced and well rounded tuning. There is imagery, detail and fluidity in abundance. There is a slightly more mid-centric warmth to the presentation. When other IEM’s have peaks and troughs, the Andromeda’s seem to forge a more average route through the sound signature without drawing attention to any particular frequencies apart from having overall slightly attenuated highs. The Campfire Andromeda signature is neutral to warm/mid-centric providing air, sparkle and intimacy to its presentation with no over-arching or fatiguing emphasis is in any specific frequency area. They are extremely well rounded, appealing and non-fatiguing for extended listening sessions. The imagery, timing and articulation are all excellent; sometime the sub-bass notes can be absorbed when there is a lot going on owing to the slightly less sub-bass energy in favour of more subtlety which I find to be pleasing and relaxing. The soundstage is wide and deep with a good sense of vertical spacing, high-hats and cymbals are less distinct. Sometimes the warm, smooth, silky mids can be slightly dominant and this is highlighted when there are passages involving the high-mids and treble. They deal with strings, trumpets and high-hats more forgivingly but with hardly any loss of detail. These are amongst the most balanced and engaging of IEMs.

Defining words: Smooth, warm, mid-centric, balanced, natural, detailed, accurate soundstage, subtle sparkle.

Comparing the Andromeda’s to the U18t’s...I found them to have slightly less sensitivity at the very lowest sub-bass registers, but then upwards of those all the way to 200hz there seemed to be incredibly even and linear response with slightly more energy between 200hz and 1k which accounts for the warmer more mid-centric presentation. The Andromeda’s followed a similar path to the U18t’s but with more energy between 8.5k and 11.5k and less from 13k upwards. This was reflected in the listening experience with the Andromeda’s sounding warmer with slightly fuller sounding high-mids and low-highs whereas the U18t’s a little thinner but more detailed and sparkly with greater air.

So it would seem that both IEMs are well balanced but with the U18t’s having the more complete sub-bass and overall brighter more analytical presentation. There seems to be just as much detail with the Andromeda’s just more subtle and at times slightly more veiled when there is a lot going on. After extended listening to the Andromeda’s you could reach the conclusion that everything is present and correct and all sounds life-like and transparent.

So what about the Noble Katana’s...? There is a good sense of overall balance, with a fair perception of neutral, the correct balance of bass, mid-range and treble. There is a slight low-treble emphasis. Vocals are detailed, textured and well rounded. The soundstage is natural, not expansive or intimate and the imagery is excellent. The sub-bass registers are outstanding with the perfect balance of sub-bass to bass balance. There is a good sense overall that they are bright enough. The Katana had no problems presenting and sustaining heavy and subtle sub-bass without bloating the bass or mid range to any extent. They have a well considered tuning giving a good overall sense of balance and order. There is a pleasing visceral sense to many of the effects and instruments owing to their excellent articulation, layering and tuning. Extended listening rewards the listener as they become more intimate and engaging without any sense of lacking in any area. The main ingredients are their impeccable sub bass and bass balance along with their sharp analytical but slightly more intimate presentation, subtle air and great timing.

Defining words: Detailed, bold, dynamic, sharp, focused, intimate, balanced but analytical.

Comparing the Katanas to the U18t’s... They are less airy than the U18t’s with a little more focus on shaping vocals and strings preferring the lower-highs to the mid-highs and high-highs. I found the Katanas to have the bass and sub-bass to lean more towards neutral and they took a different approach with the treble with emphasis on the lower-highs than the upper-highs and whilst this seemed to assist in providing more rounding and placement of instrument timbre it also created a soundstage slightly more intimate which was most engaging. There was an abundance of detail and timbre around instruments such as strings and woodwind, however the slight emphasis in this area seemed to trade off a little the sparkly end of their presentation. I think the tuning is giving a slight sibilant edge to some vocals and also providing a little more detail around strings, a signature with more shaping in the highs to give the impression of a slightly more neutral but analytical signature. Overall the presentations are quite different in particular from the high-mids upwards but both engaging.

Initial impressions diminish as time passes and ‘brain-burn’ completes you are rewarded with the perception of an absolutely complete audiophile experience. When that happens everything sounds in its right place with no sense of lacking and only slight emphasis in the low-treble. In comparison to the U18t’s which feel a little quicker and have a slightly more visceral (feel) with high intensity effects, whereas the Katanas feel a little more conventional and natural but slightly edgy in its overall presentation due to its uncompromising lower-highs. The U18t’s have slightly more energy around 3300hz. The U18t’s manage to uncover a shade more presence and instrument placement, with a wider more transparent soundstage. The Katanas emphasis on the highs (but not as much the sparkly end) of the treble accounts for its analytical and detailed presentation without seeming to lose any mid range or bass response. Slightly less airy, slightly tighter more neutral sub bass, sharper more definition around the lower highs. In its approach to detail and intensity the Katanas are somewhere between the U18t’s and both the Andromeda’s and IE800S’s often sounding completely life-like and transparent but being a little less dramatic than the U18t’s but more so than both the Andromeda’s and IE800S’s.

So what about the Sennheiser IE800S...? The IE800S’s pack plenty of punch at the low end with good, tight sub-bass and bass a plenty, but with real air and texture for example around piano hammer clunks, strings and bass drums are slightly exaggerated. Many will find this bass presentation very appealing. The mids are incredibly evenly presented and there seems to be some sibilance control here in the low-highs. There is plenty of subtle air and sparkle, which is more apparent in quieter passages not dominated by the lows and mids. The IE800S’s seem to have a frequency response which extends well into the ultrasonics but is sometimes overshadowed by the lows and mids. Imagery, depth and placement of instruments in the soundstage is impeccable despite its comparatively more recessed highs and these IEMs rewards the listener with extended listening much like the other IEMs. There are no issues with timing or articulation despite its single dynamic driver. The emphasised bass, attenuated low- treble but well extended highs make for a most engaging and polite experience.

Defining Words: Warm, smooth, addictive, textured, dynamic, organic.

Comparing the IE800S’s to the U18t’s... The IE800S’s sound more veiled, particularly in sections dominated by mids and lows. Much like the U18t’s they have outstanding imagery for depth, horizontal and vertical instrument placement. There is less air and sparkle, and a notable reduction in sensitivity between 5.5 and 7.5k which accounts for its slightly less focused and smoother presentation with vocals, strings and brass particularly in the sibilant area. I think this shaping may also be contributing to a slightly warmer presentation around the lower mids. From 8k upwards there is an abundance of sensitivity occasionally overshadowed by the slightly more intense but well textured bass response.

The IE800S’s can easily be EQ’d to reduce a little the bass response and increase a little the response between 5.5 and 7.5k producing spectacular results; however that would be robbing from its overall character of which I have come to greatly appreciate after evaluating the previous IE800 model and liking them. Note the silicon tips may also change a little the characteristics and tame a little that bass response and bring out a little more sparkle.

Extended listening of the IE800S’s immerses the listener in what becomes a transparent lifelike listening experience, rarely bothered by the emphasised bass response which many will love. This and their clever shaping in the highs result in a most engaging and non-fatiguing sound which competes confidently with the many of the top tier IEMs but providing a more mainstream tuning.

So which is the favourite...? All four are absolutely top tier IEMs I enjoy listening to for different reasons. On a sound level there is very little to choose between them apart from tuning. They all have different recipes (64 Audio U18t’s have 18 BA drivers, Noble Katanas have 9 BA, Campfire Andromeda’s have 5 BA and the Sennheiser IE800S’s have just 1 dynamic). They all deliver top levels of articulation and they can all be EQ’d to produce similar signatures bridging the differences between them. In addition all four can satisfy the demanding audiophile who patiently allows their brain to adjust to the ‘signature’ without switching backwards and forwards between them.

The Katana’s are as coherent and articulate in nearly all areas but I have a slight preference for the U18t’s sound signature, larger soundstage and sublime imagery. The Andromeda’s are more neutral than the IE800S’s and give a wonderfully warm and textured sound. The IE800S’s I could characterise as a slightly more mainstream tuning compared to the Andromeda’s in that many will appreciate the slightly emphasised bass, excellent isolation (with the complys tips) and the discrete design, and they are every bit as articulate as there multi-driver competitors which is highlighted particularly after applying EQ.

With the U18T’s I more often noticed how vivid and real things sounded often acknowledging new ideas and textures in familiar tracks. On the other hand at times some recordings sounded thin in the highs, harsh, tizzy and sibilant compared to some of the other more forgiving IEMs. As time passed more things began falling into place with undesirable artefacts seeming fewer and farther apart, with things seeming more natural. After extended time with the U18t’s I found them to present the music in the most, engaging, visceral and lifelike manner. They force you to sit up and take notice. They evoked a similar feeling as when listening to Grado’s, or Focals in that sounds just pops into being like a hologram. This is quite an achievement for an IEM and is largely what sets them apart.

I had a tough time picking a favourite and there are other candidates I could have included, however having explored the U18t’s though they are the winner for me. I feel that they are giving me as complete and refined an experience as I have yet had from an IEM more akin to open backed headphones or floor-standing speakers. There is a factor in how the U18t’s deliver the sound that has been difficult to articulate which is simply not as evident with the other IEMs and you may have noticed words like visceral, holographic, pop and texture which allude best to this. Even after ‘Brain Burn’ is completed the U18t’s are still the IEM’s that make me sit up the most taking note of the transparency. This may well be down to the ‘tia’ driver delivering more ‘air’ than any of the other IEMs. There is still room for further refinement but wonder if any adjustments to the tuning might lose some of the magic. Often you forget you’re wearing them at all imagining instead you’re listening to a high end system or live performance. A most engaging recipe I would characterise them as more mainstream than neutral.
Wow, epic post! I own the Andromeda SS and I am continuously amazed at how wonderful they sound with the SP1000M! I am intrigued with the 18t's but would consider the customs...
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Given that I own the Katana, Andro S, and I've demoed the U18t, I agree with many points you've made in your comparison of those two of your comparisons of those two to the U18t. Massive props, mate!
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Marat Sar
Marat Sar
Great review. My u18t's treble and thinness issues were fixed with the right source pairing. The source doesn't have to be a warm, "musical" one either. The ibasso dx200 titanium edition with amp4 has a sizzling treblehead sound, very reference. But the way it presents this treble is flawless. Instead of glare and tizzle it just has detail and extension. The combo is the most forgiving I've ever heard. Cable rolling, on the other hand, doesn't do much for the u18t,
Pros: Revolutionary Tia tech is an exciting innovation that sounds fantastic
Truly massive soundstage for an IEM
Wonderful layering and separation
Impressive clarity and detail throughout the entire frequency range
Extremely versatile bass response
Cons: Timbre/Tonality at times could be warmed up ever so slightly for an additional sense of realism
***After subsequently purchasing the custom A18, it seems this issue is substantially addressed on the bespoke model

Since joining Head-Fi nearly 15 years ago back in 2004, like so many others I have spent countless hours researching and reading reviews of different audio hardware in what is easily one of my favorite corners of the internet. Head-Fi is unquestionably one of the best places to meet fellow audiophiles, and to discover and learn about new headphones. That’s a great thing, because there are a lot of headphones out there! The sheer number of headphones and IEMs that exist makes it that much more meaningful when we encounter one that stands out from the rest, and is capable of introducing us to something new that we’ve never heard before.

For many, the U18t is one of those standout products.

It is truly impressive just how much technological innovation and artistry there is in the IEM market right now and 64 Audio is clearly at the forefront of it all. It takes a hell of a lot of audacity to even attempt to shoehorn 18 drivers into a single monitor, and it makes me feel a little tingly just to know that there are manufactures out there who are passionate enough to try. But knowing is only half the battle. It’s hearing that really matters. 64 Audio is well aware of this, and their slogan, “Hear Everything” is fitting to mention during this review. When you listen to the U18t, it’s nearly impossible to hear anything less.

I am writing this review while in possession of a demo pair of U18t which I reached out to 64 Audio myself to acquire. I have also had the chance to spend a good amount of time with both the U12t and Trio thanks to the recent 64 Audio tour organized by @Barra. The U18t is my clear favorite in 64 Audio’s lineup that I have heard to date. (*I have heard the Fourte as well, but I have not spent a significant amount of time with it. The sound of the U18t/U12t/Trio have all captured my attention more, and those are the units that I have spent the most time with. I will therefore not be including the Fourte here.)

I will sprinkle in comparisons between the different 64 Audio models I have heard throughout this review. I will also draw some comparisons to my personal custom Noble K10s, a virtual sonic lighthouse around Head-Fi, that will hopefully serve as valuable reference point for many others exploring the delightfully crowded world of IEMs…what a great time to be an audiophile!

*64 Audio presently allows you to spend a few days with a demo set of any available universal model of your choice. 64 Audio will place a hold on your credit card for 50% of the value of the IEM during the time you have them. Once the IEM is returned safely to 64 Audio, the hold is lifted and your money returned. The only charge for the experience is a small shipping fee (~$30.)

M15 vs. M20

The U18t currently comes with two different sets of replaceable modules that change its sound signature dramatically. When I first saw them, I wondered how these little pieces could have such an impact, but it’s hearing that matters, right? I did indeed hear a difference and my preference tilts very strongly toward the M15 (vs. the M20) modules, and this review will focus primarily on impressions using the M15 modules. The determining factor for which modules you choose will come down to personal preference, the genre of music you are listening to, or the mood you are in. The bottom line is that having options is sweet, and it only takes about 30 seconds to swap out one set for the other.

M20 – More emphasis on bass – deeper, rounder sound with more focus on low/mid impact vs. texture. Less air and high-end extension.

M15 – Less emphasis on bass...but it’s still 8(!) BA drivers working in harmony to produce low-frequency nirvana. The U18t produces fantastic bass for a BA monitor, no question. There is never a time where you feel like the U18t is producing massive bass at the expense of texture and control; at all times with the M15 modules the U18t seems to be striving to present to you a sincerely balanced, detailed, spacious and coherent aural picture across an impressively wide frequency range.

In the case of the M15 modules, less is more...much more. The real reason for my preference of the M15 modules is due to the way they enhance the high-end extension and airiness of the U18t’s overall sound. To me, it’s the M15 signature that elevates the listening experience with the U18t to the monitor’s highest level.

Sound Impressions

I feel that there are five key characteristics of the U18t’s sound that work together to create one of the most detailed and exciting sounding IEMs on the market today. In order of the significance I feel they play in shaping the U18t’s overall unique sound, those traits are:

Soundstage (30%)

High End-Extension (Tia) (25%)

Bass Impact/Power/Texture (20%)

Transient Response (15%)

Nearly Flat “Reference” Tuning (10%)

Soundstage (30%) – I do not believe IEMs are currently capable of sounding as open and spacious as over the ear headphones. After all, our outer ears do a lot to help provide us with spatial cues. IEMs pump sound directly into the ear canal leaving the rest of our ears out of the listening equation. Due to this anatomical omission, my expectations for how “open” and “spacious” an IEM can sound are less grand than my expectations vs. a headphone. Regardless of what your expectations are for an IEM, the U18t is bound to impress with its staging prowess, and the ease with which it can recreate sounds seemingly originating from somewhere far off in the distance. I’m not sure how 64 Audio accomplished this, and it’s worth experiencing for yourself.

While the U12t presents a large and wonderful spacious sound, the soundstage of the U18t is even larger; just massive really, by IEM standards. The U18t’s extra clarity, airiness, and headroom provided by the additional BA drivers helps it to best the U12t, if only slightly, in stage size. The Trio also has a large sense of space, but its soundstage is a different shape. Where U12t/U18t place you in the middle of the sound, the Trio seems to push the sound out in front of you a bit, placing you “a few rows back” and presenting a sound that is more laid back, albeit still engaging. The K10 is far more intimate in its presentation, and it also conveys a sense of space and air around instruments, it’s just not as massive and airy as the stage presented by 64 Audio. It is nice to be able to choose between a more open or more intimate stage.

I remember when I first heard the U18t back at Canjam NYC earlier this year. I was listening to Mura Masa’s I Miss You at the 64 Audio table and was amazed by both the large sense of space and deep and powerful bass. A major benefit of an IEM that can produce sounds that appear to come from outside your head, is the ability to create a sense of atmosphere. I find this tremendously enhances electronic music, especially songs that are heavily layered with complex, lush sound effects. When sound seems to come from off in the distance, it also appears less fatiguing (though, this is likely just psychological as the sound is still originating in your ears, of course.) There is also a level of excitement created as you’re constantly wondering where the next sound you hear will come from.

High End Extension (Tia) (25%) – 64 Audio’s Tia driver has stirred up a lot of excitement, and for good reason. It sounds fantastic. While some people have said that they are sure Tia is “the future,” I’m less concerned with tomorrow and happy that we can all enjoy listening to Tia right now. 64 Audio’s engineers have clearly been coming up with and building some seriously awesome tech into their products. The Tia driver is surely one of the company’s most significant recent achievements.

The theory behind the Tia driver is that with the help of some fancy engineering, certain resonance and interference commonly associated with closed BA drivers and piping sound through tubes can be removed, and a clearer and cleaner sound can be achieved. It would be interesting to speak to an audio engineer to learn more about this, but for now I’ll just trust my ears and say that the high-end presentation on the U18t is one of the best I’ve ever heard in an IEM. The U12t also benefits from the Tia driver, however there is a level of detail and extension up top that is far more pronounced on the U18t. The Trio also has the Tia driver, but the highs are rounder and less extended. Again, the Trio seems to be aimed at delivering a more laid back presentation. Whatever your sound signature preference is, 64 Audio has you covered.

The K10 does not match the high-end extension of the Tia driver, but the Noble highs are still quite satisfying and do not appear to be lacking much detail at all. A direct A-B comparison between the K10 and U18t/U12t does reveal the additional extension disparity more clearly, but the K10 still sounds great. It’s just tuned for an ultra non-fatiguing and smooth sound up top, and there are plenty of times where that may be what you’re looking for.

One instance when the Tia driver really impressed me was when I was listening to Tom Misch’s Tiny Desk Concert. Tiny Desk is a YouTube series put out by NPR and it’s an absolutely awesome mix of amazing artists, ranging from Tyler the Creator to Yo-Yo Ma. But it’s the format of the performances that makes them special: very intimate gatherings of the artists and a small crowd in what appears to be a library-like(?!) setting. The audio is very well-recorded, and each one I’ve watched has made me feel like I’ve had the chance to become better-acquainted with the artist.

At the very beginning of the Tom Misch Tiny Desk concert, right around 27 seconds you can easily hear Misch take a breath before he begins singing. However, a second earlier there’s another sound either his mouth or nose makes just before he takes the breath. I had never noticed it listening with my K10s, but on all of the Tia-equipped 64 Audio IEMs, I could hear it. It was most pronounced on the U18t/U12t, a little less so on the Trio. But hearing this kind of detail reveals just how well the Tia driver handles and conveys subtle details in the high frequencies.

Additionally, listening to orchestras with the Tia driver is a real treat. Violins sound marvelous on the U18t, and the monitor easily showcases one of, if not the best string presentations I’ve ever heard on an IEM. There is a bit less excitement present on the U12t. The Trio, with its slightly darker more laid back tuning gives up some of the sharpness from the U18t/U12t in exchange for a rounder, slightly more subdued sound.

While the K10 cannot match the high-end extension of the Tia driver, (and while we’re on the subject of violins,) it’s worth mentioning that the K10 does have a wonderfully warm timber and tonality that makes violins sound incredibly life-like. This is one trick the K10 has up its bore, and one of the reasons why the K10 can still hang with some of the newest and best IEMs on the market, like the U18t.

Bass Impact, Power, and Texture (20%) – Just thinking about the fact that 64 Audio put 8 BA drivers dedicated to pumping out glorious low frequencies in the U18t is kind of crazy. High-quality, deep, controlled, and textured bass is probably one of the most universally-lacking sonic traits in the world of average consumer-level audio. Boomy, distorted, bleeding into midrange, powerless…now, imagine the exact opposite of all of that and you’ll have a good idea what to expect with the bass on 64 Audio’s newest IEMs. Even then, you may still be surprised by the combination of impact, power, texture, and sustained rumbling capabilities of the bass when you hear it for yourself.

Many people fell in love with the original A12 because of its MOAR bass capabilities. Since the original A12, 64 Audio has been busy fine-tuning that bass. The bass on the U18t is probably the most versatile presentation of bass I’ve ever heard in an IEM. In an interview with The Headphone List, Vitaliy Belonozhko, 64 Audio’s founder and lead designer explained the logic behind shoving 8 BA bass drivers in the U18t: “The smaller the driver the faster it sounds. Because of their small size it takes 8 of them to achieve the low distortion, sensitivity and headroom that we desired.”

Low distortion, sensitivity, and headroom…check, check, check. The U18t/U12t have impact, texture and power, and can both sustain rumbling better than any other IEM I’ve heard. The U12t undoubtedly has more bass quantity than the U18t, despite only having half the number of BA drivers dedicated to the deep stuff. The main difference is that on the U18t, there is an additional level of texture, refinement, and control. To be sure, bass on the U12t is still really damn good. In fact, there is no question that many people will prefer the slight low-end frequency bump in the tuning of the U12t over the U18t. Either way, you can’t go wrong.

The Trio, with its single dynamic driver, doesn’t quite have the same level of speed and refinement as its wholly-BA crafted siblings. But, if you’re a fan of DD bass you’ll likely appreciate the Trio’s presentation. The bass presentations on the U18t/U12t are just so damn good, that the comparative the lack of refinement of the bass on the Trio, at least to my ears, just isn’t quite as satisfying…really, this is just a case of personal preference and 64 Audio stepping on its own toes here!

Bass on the K10 is very, very good, and it’s still one of my favorites BA bass presentations in an IEM along with both the U18t/U12t. But the K10’s low-end is not quite as refined as the 8BA or 4BA bass on the U18t/U12t respectively. The K10 uses two large BA bass drivers, sort of the opposite strategy 64 Audio employed using a higher number of smaller drivers. One defining aspect of the K10’s sound signature is how generously the K10 spreads its bass and warmth across the overall sound. K10’s bass does at times seem more organic vs. the more digitally clean and precise sounding delivery of bass on the 64 Audio IEMs. These differences aside, bass presentation on any of these BA-driven monitors is extremely satisfying to me. One thing I’ve always loved about 64 Audio’s monitors is their ability to confidently produce sustained rumbling. I have yet to hear another IEM manufacturer do this better, and you can be sure that the U18t/U12t/Trio will all happy deliver aftershocks to your ears.

Transient Response (15%) – Transient response can succinctly be described as an auditory “slight of hand (ear?).” Now you hear it, now you don’t. In practice, it’s how quickly you can hear an initial burst of sound before it naturally decays. When you’re listening to a complex piano or violin solo, lots of notes are presented quickly. But, just as fast as those notes come, they also need to go. This is where terms like “lightning-fast” and “razor-sharp” often get thrown around to describe initial attack and subsequent decay. The U18t performs quite deftly here, better than any other IEM I’ve heard to date.

Good transient response isn’t something that I specifically look for in a headphone. It’s a sonic trait I imagine is most appreciated by an analytically-bent listener, and I generally prefer more musicality. That said, when you combine the U18t’s transient response, the airiness of the Tia highs, the deep textured and refined bass, and the large and airy soundstage, you end up with an IEM with such a uniquely detailed sound that the detail itself actually becomes exciting. You might even also be inclined to want to learn more about what you’re hearing. I was, and the fact that listening to the U18t inspired me to further research transient response, well, that says something doesn’t it?

Compared to the U12t and Trio, the U18t is definitely faster and more technically proficient in this regard, and it surely contributes to giving the U18t a slight edge in overall detail and clarity in direct back to back listening sessions. The K10 tilts much further in the direction of musicality, and that comes at the expense of some of the most minute details that the U18t effortlessly reproduces so well.

Nearly Flat “Reference” Tuning (10%) – The last defining aspect of the U18t’s sound signature is its near-flat “reference” tuning. Much like capable transient response, flat frequency response is something one would expect to see near the top of an analytical listener’s wish list. The U12t, Trio, and K10 all have bass that’s at least slightly bumped, ensuring a generally more fun sound. But, by now it should be clear just how dead serious the U18t is about its mission to serve as the de facto “reference” monitor in 64 Audio’s lineup. There is something refreshing about hearing all frequencies presented with equal volume and importance across the U18t’s impressive range. And it is undeniably satisfying in being presented with an ultra-refined, detailed, and balanced presentation of sound in this way.


These five aspects of the U18t’s sound are what I believe most define its overall signature. This is a monitor clearly in pursuit of the sonic ideals of “detail,” “balance,” and “neutrality” at every step. Yet, 64 Audio somehow manages to infuse a higher level of excitement into the U18t’s sound than I experienced with any other monitor in the lineup, despite the seemingly more “fun” tuning of the U12t/Trio.

And this brings me to what I believe is the biggest success of the U18t, and why it stands out amongst such a large field of IEMs: the U18t finds a way to straddle the line between possessing a sound that is both supremely analytical and extremely musical, and does so better than so many IEMs that have come before it. When I listen to the U18t I hear a monitor with some of the most detail and analytical prowess, and yet, the U18t also has one of most exciting and fun sound signatures I’ve heard to date in any IEM.

What a great time to be an audiophile, indeed.
gearofwar - have not yet had a chance to hear the aether, but would love to. I have a strong appreciation for "realistic" sounding tonality.
Wonderful review! Literate, informative, usefull. I am now seriously looking at the U18t!
Great review/shootout. It's so nice to get honest reviews that don't start "This IEM was sent to me for review by..."


I was thinking, the more driver you fit into an iem, the higher the rate that somehow one of the driver inside is defective yes? How do you know if one driver of yours broke?
I was thinking, the more driver you fit into an iem, the higher the rate that somehow one of the driver inside is defective yes? How do you know if one driver of yours broke?
The most obvious way would be the fact that the IEM sounds different. In some cases, you will get a rattle if a driver is dislodged or loose. I have not had any problems yet, but if something does break (which I doubt will happen any time soon with the way Im babying my U18s), Ill let you know how I tell. Im guessing it will just sound odd.
Good GOD. 18 drivers???
Housing is tiny for how many drivers are hidden inside. You can tell it has a huge amount of drivers when listening. Such amazing layering in the soundstage and super detailed. Oh, and to clarify, that's 18 drivers per side.
Just ordered myself a pair after about a week of reading and comparing reviews on different flagship uiems, can't wait!
I agree with the overall review of U18.

U18 was a good fit for me. The Forte even though smaller wasn't. I would say the nozzle (where the ear tips are added) on the forte is smaller (your review mentions it in the reverse) and the body leading up to the nozzle is shaped like an additional nozzle and it gets in the way. It wasn't a comfortable fit.

I heard forte to have a little more clarity and resolution than U18. And U18 had a punchier bass than forte. The low and high extended a tad more on Forte. Both have different sound signature and both are equally good. It comes down to one's preference. U18 was fun and Forte was musical. Both had tonnes of details. Forte needs more volume compared to U18. It definitely draws more power.
I agree with the overall review of U18.

U18 was a good fit for me. The Forte even though smaller wasn't. I would say the nozzle (where the ear tips are added) on the forte is smaller (your review mentions it in the reverse) and the body leading up to the nozzle is shaped like an additional nozzle and it gets in the way. It wasn't a comfortable fit.

I heard forte to have a little more clarity and resolution than U18. And U18 had a punchier bass than forte. The low and high extended a tad more on Forte. Both have different sound signature and both are equally good. It comes down to one's preference. U18 was fun and Forte was musical. Both had tonnes of details. Forte needs more volume compared to U18. It definitely draws more power.
They are both great. Thanks for the feedback.
Just got a new pair. Immediate impression is that it's an all rounder with wide soundstage. Have yet to find cable that best matches it.
I recently got the Effect Audio Eros II 8 strand cable for my U18t's. Its provides a smooth and very balanced sound. Effect Audio also recommended the Janus cable but I haven't tried that yet.
I was thinking, the more driver you fit into an iem, the higher the rate that somehow one of the driver inside is defective yes? How do you know if one driver of yours broke?
Bingo. My thoughts exactly.