64 Audio U12 Universal In-Ear Monitor

General Information

The twelve driver flagship by 64Audio, and the first in-ear monitor in history to use the ADEL technology.

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500+ Head-Fier
Pros: Amazing bass response, musical presentation, wide soundstage, Apex modules, comfy housing,
Cons: Warm sound signature not for everyone.
Before review it, I would like to share technical aspect and package details.


12 Balanced armature drivers (4x Low, 4x Mid, 4x High)

3-way passive crossover

Apex M15 - M20 module

Impedance: 16 Ohms at 1kHz

Sensitivity: 115dB SPL @ 1mW

Freq. Response: 10Hz – 20 kHz

Noise Isolation: -20dB with apex M20 module


64 Audio Protective Case

48” Detachable Black Cable

Comply Ear Tips (S, M, L)

Cleaning Tool

Shirt Clip


Round Sticker

Apex Module




Design and Fit:

The shape of the U12 is quite soft and it feels really comfortable. It doesn’t have sharp edges. It is also, extremely lightweight, so you can listen without any pain, even if it stands for 3 hours on the ear. U12 has 12 armature drivers inside, but the housing is quite small. I like the design and fit.




This was my first listening with Apex technology, so I was a bit concerned about isolation. But when I heard it, I realized that my worries were irrelevant. Isolation is quite good with Comply foam. It has very similar isolation with the silicone tips as well.



Sound Type:

I would explain U12 with the simplest words; warm, analogue and musical earphone. Really musical and you can listen very enjoyably. U12 is a tad dark but It's not as dark as like Um Pro30.

I would call All-Rounder for U12. All kinds of music can play really well at the optimum level. The dynamism and energy of the U12 is also very nice. In general; slightly powerful lows, little laid back mid and relaxed treble.


The U12 has smooth and relaxed treble. It is also nicely tamed. The amount of treble is very prominent than I expected. Because of the sub-bass area is too powerful. Really powerful. Trebles stand a bit more forward than the mids. It fast and it has good level of detail, but still not the star of the show. There is no harshness, sharpening or aggression. In the fast passage in the music it doesn’t lose control. Also, there is no sibilance.


The Mid frequencies generally a little bit lack but not too much. It stayed laid back presentation that is slightly the bass and treble and it does not lose anything from its detail. Vocals have a very analogue feel and presentation. Laid back mid presentation creates a sense of spaciousness and a wide range of soundstage. Space between of the instruments is extremely natural and clean. I especially love the guitar sounds. My favorite aspect of vocal presentation was sweet-soft vocal presentation. I especially liked the voice of female vocals more than male vocals.

The U12 has warm, meaty mid. There is no harshness in the upper mid.


Bass is the best area of the U12. It has powerful, accented, tight basses. Although sub-bass is not going very deep, they are powerful character. The overall presentation of the earphones dark and warm, I expected to dominate the other frequencies a little bit but I didn’t find it in the sources of the music I listened to. The bass is a little bit slower in the EDM (High BPM Progressive House / Trance), but this slowness is not the dynamic driving slowness. With the U12, I always listened to the music that was like Deep House, Progressive House, etc. Because it has really enjoyable bass response and they pushes you to listen to bassy tracks. This is the best bass I ever listened from armature drivers.


The soundstage of U12 is as wide as the Apex module itself. It has a pretty big soundstage.

Positioning in the soundstage is pretty good. It gives you the sense of a stage being there in front of you and when positioned properly you can easily feel like you are at the show. All the instruments come very close to where they need to be, and they can easily be distinguished. Instrument realism and dynamics are really good.


It is the one of the most enjoyable, favorite earphones I have ever listened to. It has superior detail and resolution. It is very enjoyable to listen to EDM. I would recommend using SPC or Silver cable if you are going to upgrade your cable. If fun factor is important for you and if you are looking for a wide soundstage, deep, powerful bass, musicality then you are looking at the right product.
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100+ Head-Fier
Pros: Decent isolation, Comfortable form factor, Satisfying and visceral bass, Extremely musical, Smooth and easy to listen to
Cons: Limited tips provided, Sound signature not for everyone, Warmth doesn’t play nice with slower genres


Disclaimer: The 64 Audio U12 was provided to me as a loaner by 64 Audio for the purpose of this review. This will in no way affect the review whatsoever. This review, as always, will be objective and reflect my honest thoughts and opinions on it.

I would like to firstly thank Vlad of 64 Audio for loaning the U12s to me to review. I met Vlad at CanJam Singapore 2017, and after talking to him for a period of time regarding ADEL and apex, as well as tia, I introduced myself and showed him my previous review. After expressing interest in reviewing 64 Audio’s IEMs, he agreed and things just fell into place.

I really appreciate the support that Vlad and 64 Audio has given me, considering I only have 1 previous review under my belt. With that being said, objectivity is still at the core of my reviews, and will always be. This review is no exception.

Again, please bear with me. This is yet another rather lengthy review, as I would like to leave no stone unturned and be very detailed as to portray as accurately as possible to you – the reader – the overall sound profile as well as the benefits and sacrifices that apex brings to the table. There will also be a comprehensive comparison between ADEL and apex as part of this review.

All of the pictures in this review was taken by me, if you guys need to use them for whatever purpose, do let me know and link this review. I hate to put watermarks on my images so this is greatly appreciated!

As always, this is just my second review; any feedback would be welcomed! I decided to change things up a little for this review and be a little more comprehensive in my comparisons. Do let me know how did that go! Huge thank you to everyone for the support! :)



Decent isolation, Comfortable form factor, Satisfying and visceral bass, Extremely musical, Smooth and easy to listen to


Limited tips provided, Sound signature not for everyone, Warmth doesn’t play nice with slower genres


64 Audio was initially known as 1964 Ears prior to their (now defunct) partnership with Asius Technologies. They have an impressive clientele which includes Beyonce and Seal, just to name a few. They have recently announced 2 new Flagship IEMs which utilizes the TIA technology. Also, known as Tubeless In-ear Audio, tia involves a completely tubeless system using the newly developed tia driver, which unlike typical balanced armature driver design, does not have a tube where the sound will come out of, but rather the driver itself is completely open.

The tia Fourte is the first in-ear monitor in the world to fully utilize the tia technology and the A18 Tzar is the first 18-driver in-ear monitor in the world, a testament to 64 Audio’s commitment to innovation and technological advancement.

With that said, 64 Audio has a rather impressive line-up, starting from the A2e for the budget-conscious to the state-of-the-art tia Fourte for those who demand the absolute best, 64 Audio has something for everyone.


Prior to the launch and release of the tia Fourte and the A18 Tzar, the U12 was the universal variant of 64 Audio’s previous flagship, the A12.

The universal U-series was intended for consumers and musicians who does not want to go through the trouble and the process of getting a custom in-ear monitor but still demand high audio-fidelity from their earphones.

In lieu of the recently launched tia Fourte and the A18 Tzar, it would be interesting to see how the U12 stands up against them and with new IEMs being launched every other week, it would be interesting to see the U12’s performance in such a competitive market.



The unboxing experience on the U12s was very well thought out. The box itself was surprisingly small and consists of 2 parts.

There is the outer sleeve, which is white and the front has the 64 Audio logo with a picture of a set of their U-Series IEMs with the bottom stating just that. The front is flanked by 64 Audio’s tagline, “hear everything” on both sides.


The back has the history of 64 Audio shown on it as well as a short introduction to the apex technology. Below that shows the content of the box as well as other miscellaneous information.


Removing the sleeve reveals a red box with a rather epic picture of an artist on the top with the 64 Audio tagline yet again on the bottom.

IMG_7842.jpg IMG_7843.jpg

Opening up the flap will reveal the content of the box. 64 Audio has also cleverly placed the quick start guide at the back of the flap rather than including a card or booklet. The top tray houses the dehumidifier as well as the tips. Below that is the case and in it, the IEMs themselves. 64 Audio also has included a sticker.



64 Audio U12

64 Audio IEM Case
Shirt Clip
Cleaning Tool
1 set of Dual Flange Silicone Tips
3 sets of Comply Foam Tips (S,M,L)
64 Audio Sticker

While not as comprehensive as the Empire Ears accessories package, the accessories that 64 Audio includes with the U12 is no slouch either. One item in particular that stands out to me is the dehumidifier. Not a lot of IEM companies includes them in their accessories package and I usually have to get mine from shoe boxes or purchase them separately, so it’s nice that 64 Audio has decided to include them.

If there is something that I found disappointing about the accessories is the provided tips. For a product of this price and considering how it was the Flagship IEM from 64 Audio, the tips that were included were rather disappointing. It’s no deal-breaker, but I would’ve preferred them to at least include a set of regular silicone tips in small, medium, and large size.

However, I would like to take this moment to express how well thought out the 64 Audio case is. It is small, compact and it is very practical. It is even smaller than the Pelican 1010!

In the case, there is a cut out for the provided dehumidifier, the cleaning tool, and shirt clip, there are even slots for 2 extra pairs of apex modules! The slots that house the IEMs are also very well thought out. It is lined with rubber to protect the IEMs themselves from any impact or shock, and there is a pop-up slot for cable winding and 4 slots for placing the 3.5mm jack in.

Here’s the thing, no matter how I winded my stock cable, I always found the jack to line up perfectly to 1 of the 4 slots for the jack and although it is something very minor, it shows how much thought 64 Audio put into designing this case.

However, this case might be too small if you are planning to swap the stock cable out for an upgrade cable.

Construction and Finish


The U12s are made of plastic, which is normal and rather common in universal IEMs. However, 64 Audio opted for a more subdued and simple design. The entire IEM is glossy black with the 64 Audio logo and the port for the apex modules on the faceplate.

While some may argue that the design may be too plain and simple for an IEM of its price, personally I think it’s fine. The minimalistic looks give it a sense of class; the glossy black is reminiscent to a grand piano. The surface does, however, attract fingerprints, but since it is black, it is not really noticeable.

The IEM itself is very solidly built and does not feel cheap. The review loaner I received has no imperfections on the shell either.

The shell is rather small too, unlike other 12-driver IEMs like the Layla 2. It is quite amazing how 64 Audio managed to fit 12 drivers into such a small shell, and not to mention the slot for the apex module as well.


The small shell is rather ergonomic, and I achieved a good fit very easily. With that said, as the U12s are a universal set of in-ear monitors, the fit of the U12s are highly dependent on the tips, and as I have mentioned above, the tip selection that is provided with the U12s are less than stellar, which might be a problem for some.

Personally, I find the final audio tips that were given out during CanJam Singapore to work best for me, with the SpinFits coming to a very close second.

Tip Rolling

As tips are an integral aspect of every universal fit in-ear monitors, I decided to include a section on tip rolling, as I do believe that the choice of tips does change the sound slightly.

Final Audio Tips

The Final Audio tips are by far my favorite tips to use with the U12s, period. They are extremely comfortable and provide a very clear sound without dampening any treble or over-emphasizing the bass response.

Verdict: Highly Recommended


The SpinFits fit extremely well as well. They are comfortable but I do find them to “push” the IEM out of my ear canal after some time of use, and I would have to push them back into my ears. However, they too, provide a very clear sound very much like the Final Audio tips.

Verdict: Highly Recommended.

Spiral Dots

The Spiral Dots are technically incompatible with the U12s as the nozzle is too long and the tip of the nozzle will peek out of the ear tips when inserted all the way, which can cause pain during usage.

A popular workaround would be to use O-rings or to cut the stem of another pair of tips then inserting that before inserting the Spiral Dots. Personally, I tried that but that resulted in the tips popping out of the nozzle when removing the IEM and getting stuck in my ear canal.

In terms of sound, they reduce bass and accentuate the treble slightly. However, getting the tips to fit onto the nozzle is too much of a hassle in my opinion and thus, I would not recommend them.

Verdict: Not Recommended

Comply Foam Tips

The Comply foam tips are provided together with the U12s in 3 sizes; I used the medium size. They are extremely comfortable and fit very well.

However, they do dampen the treble and increase the bass response which I feel would not benefit the U12s due to its sound signature (more on that later on). But they are very comfortable and fits very well so I will still recommend them.

Verdict: Recommended

Stock Dual Flange Tips

The stock dual flange tips are relatively comfortable, but they do irritate my ears slightly as I am not used to using dual flange tips. In terms of sound, they provide a slightly reduced bass response. Overall, I would recommend these tips over the Comply Foam Tips.

Verdict: Recommended



Do note that the section on sound is written based off the U12s with the stock cable using the default M20 module running out of an AK380 with primarily lossless FLAC files and some 320kbps MP3 files.

I would like to thank Calvin of Music Sanctuary for loaning me the Astell&Kern AK380 + Amp. One feedback that I received and an aspect of my previous review that I was not satisfied with from my previous review was my poor sources. And so, Calvin has very graciously loaned me a set of the AK380 + Amp to aid in improving the quality of my reviews.


The soundstage on the U12s is very wide and spacious. This is without a doubt, partly due to the apex technology. The soundstage is also extremely holographic; instrument placement is distinct and well defined.

While the soundstage is wide and spacious, the overall sound is still rather intimate and upfront. This is unlike my experience with ADEL in-ear monitors, as they have a rather distant overall sound. The U12s however, do still have a very immersive soundstage presentation, putting the band right in front of you; and it’s easy to get lost in the music.


The bass on the U12 is probably the most prominent and outstanding aspect of the sound signature. The bass has rumble and authority, it is punchy and has great depth. Bass impact, however, is not very impactful and you won’t get the “slam” that you can sometimes feel in your eardrums when using IEMs with a stronger bass presence, and my guess is that this can be attributed to APEX.

Therefore, while the bass is strong, I would not call the U12 a “bass head IEM” as it just does not have that slam and soul-shattering impact. It also does not have enough presence and authority to be classified as a bass head IEM as well.

Attack and decay is impressive as well; it is not extremely fast nor is it slow, it is just right which gives a very natural presentation of the bass, not overly energetic or sluggish. Still, it manages to keep up with a lot of fast tracks with ease.

The Sub-bass is very well articulated and depth and texture is incredible. It is as authoritative as the bass but sometimes, it can bleed into the mid-range.

One of my favorite test tracks for bass is Gooey by Glass Animals. As mentioned above, while the bass impact is not extraordinary, the details in the reverberation, as well as the articulation, is outstanding; I could hear the “airiness” in the reverberation and the bass sounds very natural.


The midrange on the U12 is of a warm tonality. Although they are not forward, the mids sound very intimate and sweet. The most prominent factor of the midrange is how smooth and lush they sound. In fact, the U12s have one of the smoothest midrange that I have heard in an IEM, albeit, that number isn’t staggering.

Because of the smoothness and lush of the midrange, coupled with its warmth, the U12s is a very musical piece. However, this comes with a trade-off that is the resolution. The U12s are not the most resolving piece, which may be a deal-breaker for some, however, the musicality of this IEM is extremely outstanding.

I really like the vocals on the U12s. When I listen to Happier from Ed Sheeran’s Divide, vocals sounded extremely sweet and intimate; it is as if Ed Sheeran was singing right in front of me. Overall, the mids sound very personal and intimate; sweet, smooth and very easy to listen to.

However, just like the Empire Ears Athena, I personally feel that the midrange is too warm for classical or piano music. They will still sound good, but I do feel that they will sound a tad unnatural.


The treble is the most polarizing aspect of the U12’s sound signature. I have had people who tried the U12s complain about how subdued and rolled off the treble sounded to them and on the other hand, I’ve had people who were extremely satisfied with the treble, describing it to have “just the right amount of sparkle”.

I feel that the treble on the U12s is an acquired taste. Some airtime with the U12s is needed to fully understand and appreciate the treble. While the treble is not very extended, they are not rolled off per se. With that said, the treble does have a very natural tonality.

The treble is not sharp, and I highly doubt anyone would think of them as sibilant. There is a very nice sparkle to it, and it is fast enough to keep up with most genres. They are a little softened and smooth; which adds on to the musical signature of the U12s.

While the separation and micro-detailing are not as transparent and clear as some other monitors such as the Empire Ears Zeus, nor is the extension particularly outstanding, they do have a certain airiness and smoothness in the treble, which is actually rather pleasing.

There is also a certain degree of resolution to the treble. It is not the most resolving but it is definitely no slouch as well. The cymbal clashes in Back in Black by AC/DC are very clear and very nicely articulated.

Overall Signature

Overall, the U12s have a very musical signature and it is very enjoyable and easy to listen to. There is an aspect of “fun” in the sound signature. The U12 is a very versatile IEM with its warmth, authoritative and powerful bass, coupled with the smoothness of the overall sound signature. It plays very well with almost all genres, with slower music being the exception. I feel that some forms of acoustic as well as classical or orchestral music do tend to sound a tad unnatural because of the warmth of the U12s. Don’t get me wrong, they still sound excellent, just a little unnatural.

With that said, the U12s are very intimate sounding; the sound is upfront and personal. I really enjoyed listening to vocals especially on the U12s as they sound extremely sweet and with the intimacy of the sound signature, it is as if the artist is performing in the very same room. Genres that excels for the U12s, in particular, is Rock, Pop, and EDM. With the visceral bass and the warmth of the U12s, they really bring out the energy and life of the said genres.

While not the most resolving monitor out on the market, the U12s have a very musical sound signature that is very forgiving. It's softened and slightly distant treble and visceral bass response is not for everyone out there, but for those who enjoys a more musical sound will definitely enjoy the U12s plenty.


The U12s are very forgiving to both sources and recordings. It sounded extremely pleasing out of my iPhone running Spotify Premium but the U12s will also scale very well with better sources and recordings. IT will also benefit from additional power. I always prefer the U12s on the AK380 + Amp versus the AK380 alone. The added power of the AK380 Amp really opens up the sound giving it better imaging and resolution.



Apex is a 64 Audio in-house technology that ships with every 64 Audio IEM apart from the tia Fourte. The principle is simple; using a pneumatically interactive vent, apex relieves pneumatic pressure in the ear, providing a more open soundstage while reducing ear fatigue. Apex also allows the varying of isolation levels for different sound flavors.

Currently, there are only 2 different types of apex modules that are available on the market: the M20 and M15.

M20 vs M15

The M20 provides more isolation than the M15, having 20db of isolation versus 15db, hence the names M20 and M15. While not up to the level of custom in-ear monitors, I found the M20 to have excellent isolation, at least as good as most of the universal in-ear monitors on the market. However, the 15db is not bad either. Generally, I don’t really hear much of the ambient noise with both modules.

In terms of sound, the M20s has a smaller and less open soundstage than the M15s. Bass response is stronger and more visceral and authoritative on the M20s.

However, with the M15s, vice versa to the M20s, have a wider, more open soundstage. Bass response is more controlled and sub-bass no longer bleeds into the mid-range. Resolution is also better as the bass is now more controlled, and it is now easier to hear all of the finer details. Also, due to the lowered bass response, the U12s do sound a little brighter relative to the M20.

Personally, I highly prefer the M15s as they control the bass and give the U12 a more open sound.

Apex vs ADEL

I would like to thank Calvin of Music Sanctuary yet again, for loaning me a universal demo unit of the A12s that is able to fit ADEL modules for the purpose of this comparison.

Here is where things get interesting. In principle, both apex and ADEL is out to achieve the same thing: a more natural and open sound while reducing ear fatigue. ADEL goes further and states that with ADEL, you will get a higher perceived volume and thus, will listen to a lower volume level and by extension, save your hearing.

ADEL uses a membrane that will absorb pneumatic pressure in the ear canal when listening to music. Meanwhile, apex uses a special type of foam that “activates” when pneumatic pressure is present, and then venting the said pneumatic pressure.

Ever since getting my Empire Ears Athena-VIII ADEL, I have been interested in comparing the differences between apex and ADEL as I could not find any detailed comparison between the both.

And I believe many of those who are still on the ADEL 64 Audio IEMs would be interested in seeing how they compare as well as is it worth it to upgrade to the new apex modules.

With that said, the comparison is still done on the U12s, in which I will make reference to the U12 sound signature. This comparison is most valid for the U12s and might not apply to the other models but I do hope that it might give you a general idea of the differences between the apex and ADEL modules.


Without a doubt, the apex modules have superior isolation to the ADEL modules. Specifications of isolation levels on paper aside, I never heard ambient noise on the apex modules that I do on the ADEL modules.

Like I mentioned in my Empire Ears Athena ADEL review, isolation is sub-par when using the ADEL technology. In fact, the isolation is so poor that even with one of the touted ADEL benefits being higher perceived volume, I found myself to be turning the volume up even further to compensate for the loss in isolation.

Ear Fatigue

There is this controversy that I saw on the 64 Audio thread while I was doing some research for this review regarding the effectiveness of apex.

Personally, I care less for claims and specifications that have been made on paper and I care more about my personal experience. Personally, I have issues with ear fatigue and IEMs. I would get ear fatigue after listening for an hour and I would need to remove the IEMs in order to rest my ears before continuing.

When using the ADEL modules on the U12s, like my experience with my Athena ADEL, I do not get any ear fatigue whatsoever. I am able to use the U12s for hours on end.

Now, here comes the part where some of you might disagree with me: I get the same experience with apex. When I use apex, I do not get that ear fatigue that I am so familiar with. Therefore, in my opinion, and in my usage, apex works as well as ADEL.

As always, YMMV and what I experience may not be the same as what you experience.

M20 vs S1

Soundstage is wider on the S1 than the M20. The sound is also ever so slightly more open. However, with the S1, it does make the sound a little distant and less intimate. For some reason, I found the sub-bass to bleed into the mids more on the S1 and there is a now a veil over the midrange that isn’t present with the M20s which is rather peculiar. The veil is more obvious when I use the S1 module on one side and the M20 on the other.

M20, on the other hand, has more bass and a more intimate sound. Soundstage is not as open but the sound is less distant. Resolution is also better on the M20 due to the distant sound that the S1 brings to the U12.

I also found the S1 to sound a little weird with the U12s. On the S1, the bass is not as punchy or authoritative or visceral but there is still the strong sub-bass. Which I did find a little weird sounding as there is the sub-bass without the bass. There is also the matter of the veil over the midrange which I cannot put my finger on.

I found the M20 to sound better than the S1 as overall, not only is there a better bass response, the sound is also more intimate and does not have that weird veil over the midrange. The S1 just doesn’t sound “right” on the U12s.

M20 VS G1

The G1 again has a wider soundstage than the M20s. Bass response is also elevated when compared against the M20s. I did find the sub-bass to bleed a little more on the G1 as well. Bass is punchier and tighter on the M20s. There is also the distant sound that is characteristic of the ADEL modules.

Resolution is better on the M20s and has less bass and sub-bass presence than the G1. Notice I used the word “presence”. That is because the G1 brings the bass forward but does little else. With the G1, I found the bass rather overpowering and uncontrolled on the U12s. The irony is, I am not getting fatigue from the overpowering bass of the G1.

Personally, I am not a fan of the G1 on the U12s. The bass is just too overpowering and uncontrolled. The M20s provide a tighter and punchier bass response but also a more controlled one, and the sub-bass is not bleeding too much into the midrange.

M20 VS B1

Alas, the famed B1 and U12 combo. The B1 module opens up the soundstage of the U12s and in my experience, has a similar bass response to the M20s, although, I did found the sub-bass to have less presence and the bleed is now gone. As always, the distant sound characteristic is present.

There really isn’t much to say here. The B1 is basically an M20 with a more open soundstage and lower sub-bass presence. Resolution is better on the M20s but that is only very slight.

Personally, I prefer the B1 to the M20 as the sub-bass is now more controlled and is not bleeding into the midrange. The larger and more open soundstage is also a huge plus.

M15 VS S1

The M15s has a larger and more open soundstage than the S1. There is also less bass on the M15s than the S1. Bass is punchier and tighter on the M15. It is also more controlled and there is no bleed into the mids whereas the S1 as mentioned above, has that bleed. Resolution is better on the M15 as it does not have that distant sound that ADEL has.

With the M15s, the veil of the S1 is now even more apparent, and so is the sub-bass bleed.

Overall, not a fan of the S1 on the U12s. It just makes the U12s sound weird and veiled.

M15 vs G1

The M15 again has a wider and more open soundstage than the G1. There is also less bass on the M15s as compared to the G1 where it has that overpowering bass on the U12 as mentioned above. Resolution is better on the M15s as well with thanks to the tighter and more controlled bass response.

M15 vs B1

The M15 yet again has the wider and more open soundstage. It is airier than the B1 and has less bass as well. Bass on the B1 is more prominent and authoritative than the M15. As such, resolution is better on the M15.

Overall, I found myself to prefer the M15 over the B1 on the U12s as the U12s really do benefit from the less bass response and more open soundstage.

Apex vs ADEL Conclusion

Overall, I do prefer the M15 over all the other ADEL and apex modules for the U12s. The airiness and the open soundstage paired with the lowered and more controlled bass response do in my opinion, bring the U12s to the next level.

With that said, YMMV and you may prefer the other modules be it apex or ADEL. I hope this comparison will give you a better understanding of how the ADEL and apex modules compare to each other, even though it was made in reference to the U12’s sound signature.


All comparisons were done with the U12s on stock cable and M20 modules. The AK380 + Amp was used for all comparison.

64 Audio U10

The U10s were on the M20 module for this comparison.

The soundstage on the U10s is slightly wider than that of the U12s. This is probably due to the differences in sound signature.


Bass on the U10s is definitely not as strong or authoritative as the U12s. Bass on the U12s are more thunderous and have much more presence. Bass rumble and texture are also better on the U12s. Bass on the U12s are also deeper and has better sub-bass extension.


Mids on the U12s are more sweet and smooth than that of the U10. It is also warmer and more intimate on the U12s.


Treble on the U12s sound distant in comparison to the treble on the U10. The treble on the U10 is more aggressive and “in your face” than that of the U12. Treble extension is also slightly better on the U10 than that of the U12.

Empire Ears Zeus XR

I swapped the cable on the Zeus XR to a stock plastics one cable in order to reduce the confounds and focus the comparison on the sonic differences of both the monitors alone.



The soundstage on the Zeus-R is wider than that of the U12s. The Zeus-R has a more spacious and open soundstage while the U12s are more intimate.


Again, bass on the U12s is much more authoritative and stronger as compared to the Zeus-R. Although, bass on the Zeus-R is tighter. On the other hand, sub-bass extension and rumble is better developed and articulated on the U12s.


Mids on the U12s are fuller and lusher sounding. They are also warmer and more intimate. They are also smoother on the U12s.


Treble extension on the Zeus-R is airier than that of the U12s. It is also more aggressive and has more of a sparkle on the Zeus-R. Treble resolution is also better on the Zeus-R. The U12s have more of a laid back and softened treble as compared to the Zeus-R.



The soundstage is wider and more open on the Zeus-XIV than the U12, but the difference in soundstage is not as much as the Zeus-R.


Bass is more visceral and authoritative on the U12s. It reaches deeper and has more texture and resolution than the bass on the Zeus-XIV. Although, the bass is tighter on the Zeus-XIV.


Mids on the U12s are warmer and sweeter sounding than the mids on the Zeus-XIV. They are more intimate and smooth on the U12s as well. I did find the mids to be more lush on the U12s but not by much.


The treble, like the Zeus-R, is faster and airier on the Zeus-XIV than the U12s. The treble on the Zeus-XIV is also more aggressive than the treble on the U12s.

Noble Audio Katana


The soundstage on the Katana is decisively larger and airier than that of the U12s. But then again, this might be attributed to the Katana and the U12s are going for different sound signatures, with the Katana going for accuracy and the U12s going for musicality.


The U12s has a bass that is more prominent and authoritative than the bass on the Katana. The Katana has a bass that is more controlled, tighter and punchier than the U12s. The U12s have more rumble and texture in the bass but the Katana has more resolution and micro-details.


The Mids on the U12s is warmer and sweeter than that of the mids on the Katana. Though, the mids on the Katana sounds more accurate and natural to my ears. I found the mids on the U12s to be smoother but not by much when compared to the Katana.


The Katana has better extension and air in the treble. Resolution is also better and the treble has more sparkle. Treble on the U12s are smoother and not as prominent.

Noble Audio Kaiser Encore


The soundstage on the Kaiser Encore is, like the Katana, wider and airier than that of the U12s. However, the difference is not as much as the Katana. Again, this could be attributed to the difference in sound signature.


Bass is stronger and more visceral on the U12s. Sub-bass has more presence and authority. There is also more texture and rumble in the bass. However, the Kaiser encore has a tighter and more controlled bass. It is also punchier on the Kaiser Encore.


Mids on the U12s are decisively smoother and warmer than the mids on the Kaiser Encore, but not by much. The Kaiser Encore still has mids that have a more natural tonality, versus the warmth on the U12s


Treble on the Kaiser Encore has more sparkle and resolution than the treble on the U12s. They are also more upfront and aggressive compared to the smoothened and slightly distant treble of the U12s.

Final thoughts


The U12s are a very special piece by 64 Audio and is worthy of its flagship status (although, its flagship status has been displaced by the U18 Tzar and tia Fourte). In a market where most flagships usually go for resolution and balance in their sound signature, I have to give credit to 64 Audio for daring to opt for a more musical, slightly darkened sound signature with the emphasis on the bass.

With that said, the U12s are not for everyone. Not everybody likes smoothness and musicality, and not everyone likes a sound signature with an emphasis on the bass, but those who do will feel right at home.

The U12s are a solid package with my only complaint being the provided tip selection, but really, that is very easily resolved. With the apex technology, the U12s prove themselves to be a very solid piece and one that I would easily recommend to anyone who is looking for a musical IEM.
@linux4ever: Thank you very much!
@PinkyPowers: Thank you for the kind words! Hmm... I believe I may have poorly worded my M15 vs B1. While I found the bass to have more overall presence with the B1, the M15s did indeed have a punchier bass. I think it is just apex vs ADEL in general; apex modules gave the U12s the "bite" and punchiness of the bass that ADEL took away. I cross-compared this with my Athena ADEL as well.
Overall, I thought that the apex modules have a much better bass response than the ADEL modules in general.
Relatively concise for the amount of information displayed, and accurate and comprehensive sound impressions to boot. Well done!
I've been waiting, thanks @PokerFaze. Very impressive review. Amazing effort. Nice photos in addition.


Reviewer: Audio Rabbit Hole
Pros: Smooth sound, Great fit, Long listening without fatigue
Cons: Expensive, sound signature takes some getting used too

I love music and I love good quality sound and this is my hobby. I prefer to find the best portable setups available as I do not like to be stationary. I do not want to be tethered to a desk with an amp, and for that reason I have never bought a desktop rig. If I want to walk away, and make a drink, I want to pick up and go while still listening to music. In other words, enjoy excellent sound whether I am walking the dog, going to the gym or hanging out at the pc. I don't rely on graphs or charts, when I listen to music my ears tell me what I like, not my eyes. 
64 Audio U12/Adel-S1/B1 Module
-MRSP (Universal): $1599 w/S1 module
They say idle hands are the devil's workshop, and I must say that phrase has my name written all over it! I actually was at a point where I was quite satisfied with my stash of gear at the time and my go to IEM was the Rhapsodio Solar. I reached a conscious decision to finally settle in and sell of some gear and fade into head gear and HeadFi obscurity. I have reached end game NIRVANA no more buyer's remorse no more splurging, no more floating credit 
.  I have no will power and had to take the first step in curing my problem and I admitted I had a problem so I bought another iem and succumbed to my demon. That demon iem is the 64 Audio U12.

I must thank a fellow HeadFi'er who was willing to feed my habit and I purchased an excellent condition, low hours U12, with the S1 module. Thanks Jozzur!
Honestly, I am not sure why this IEM was on my radar, but it was. There are many options in the $1000.00 - $1500.00 used range. I mean folks love the 64 Audio U6, the Andromeda, Empire Ears and so on. I already had the Solar with 10 drivers and I loved them...addiction is a bitch!  What really drew me to the U12 was the fact that I am sure my hobby has contributed to the fact that I have tinnitus and here's hoping that the Adel modules will help with that and more drivers has to be better...right?
After we made the deal I began to do more research, which I know is the reverse of what normal thinking people do. The purchase came with everything stock including the S1 module and in my research the S1 was not the module of choice, the S1 appears to create a veil and a bassy signature. I searched the sale threads for a B1 which appeared to be the module of choice for the U12. But alas no one had one for sale. 64 Audio has also made the choice to switch from Adel to Apex so I was becoming more confused and frustrated, and then you throw the MAM module into the mix and this was becoming more than just a plug and play decision.
 This is the company that created the ADEL modules. Rather than waste more effort I ordered the B1 module retail direct from these guys which many think is the preferred module for the U12 creating a more balanced, airy and open sound. The order was immediately shipped and I actually had it before my U12's arrived. Thanks for the quick service!
I would still like to hear the MAM module and if I have the opportunity I will edit the review to include that module.
When the U12 arrived I was excited to take in all of the glory that was the U12. WOW, a rather small, unimpressive package, with a sinking feeling I opened the 64 Audio box to ONLY be equally underwhelmed at the hard case that I was looking at! I opened the hard case and I saw a plain black acrylic shell with a thin black cable. The first thought that came in my head was there is always the For Sale thread and to chalk it up as another life experience, shame on me why did I spend so damn much. I was expecting that face melting Indiana Jones, Holy Grail experience.
There are plenty of unboxing videos and photos of the 64 Audio products so you won't find that in this review, accessories are the basics to get you by and the packaging is minimal, enough said. 
On to the show:
Comfort is really good. Considering there are 12 drivers it is pretty amazing how comfortable these are. There were two things that made me sell the Layla, ergonomics and seal. The Layla were like Frankenstein bolts and fortunately the U12 are not. They are well designed, comfortable and I can use them for hours without discomfort.
The stock cable is thin, light, and flexible and feels very average overall. The review I am writing is not using that cable, I have a couple of Rhapsodio cables and after a brief listening session with the stock cable I switched to a Silver Litz 4 braid cable. I also have the SPC Pandora by Rhapsodio but I have not tried it as the Silver Litz is more comfortable than the stiff copper one. I am not a big believer in a cable changing a sound signature as opposed to impedance changing the sound. However, I do like more comfortable cables so I used the Silver Litz option I had.
I have tried many eartips in my time with this hobby, but when fit permits, I always seem to prefer the JVC Spiral Dot tips and it's large bore and with the U12 it is no exception. I will say I am fortunate to use large tips with this IEM because they have a very long nozzle and any size but large will leave nozzle exposed, and lord only knows we can't have our nozzles exposed. I am using the Spiral Dots for this review.
I have used two sources during this review and they are my Google Pixel Xl and a Cayin i5. The Pixel is pretty standard listening but really not bad and the Cayin i5 which has been characterized as a warm, but clear sounding dap. The review is not about the dap but I will say the sound signature of the i5 has changed with time for the better and this dap is powerful enough to drive the HD650 so the more time I spend the more impressed with the sound I become. The detail and openness of the i5 are starting to become more apparent.

When I started to write this review I poured a Barbancourt 8 year and Diet Coke and put the U12 in my ears with some Metallica as motivation. At this point I am on my second beverage and have passed Metallica and Praxis(Transmutation Mutatis Mutandis) and am on to some Red Hot Chili Peppers,The Getaway. 
Upon first listen with the stock cable and the S1 module I could not believe what I was hearing. This was the most polarizing, confusing sound I have ever heard in an IEM. The frequencies seemed jumbled and the high end was weirdly mixed into the sound and they were a warm, thick sound. I went back to my comfort zone and put the Solar in my ears...ahhh relief. I prefer a musical, slightly warm sound for my headphones and IEM's but this was an entirely new level of warmth. I never crave treble and loathe anything that can be strident or harsh but I found myself wishing for treble.
The 64 Audio U12 contains a dozen Balanced Armature Drivers in each ear, four bass, four mids, and four highs. With the ADEL S1 Module, the U12 is surprising how warm an IEM can be. A switch to the B1 module and there is air and a wide soundstage. The details shine through with a tonality and smoothness that creates a relaxing smooth listening experience. Thank God for the B1 module. I would be curious now that I am accustomed to the sound if the S1 is still off sounding to me maybe one day I will try them again.
The Silver Litz cable and B1 module have been the setup I have stuck with. For the review I am using the Cayin i5 with the U12, Spiral Dots and Silver Litz cable. 
I gave the U12 a lot of time before writing this review and now I must say I am a believer.....what a great sound!

The bass on U12 is deep in the sub level and detailed with layers in the mid bass range. The overall sound signature is warm but the tone of the bass and layering of the bass range is awesome, one of the best I have heard... bar none. As a comparison the Angie's level of bass could be increased but can't reach the detail levels of the U12. The Solar has excellent bass detail but is still bested by the U12. The Heir 8.0 has a bass presence throughout the signature, however the quality is not on par. There are layers and textures in the U12 that extend deeper than many over ear headphones I have heard. Color me warmly impressed!
The mids are clear and incredibly detailed but you will not realize this when you first listen to the U12, they appear to have a bit of a veil. With brain burn-in you realize there is not a veil at all it is how the frequencies are served up. The tone of all vocals shine and with male vocal sounding strong and females sounding sexy. The soundstage is good and the imaging was providing me with some occasional nice effect. The U12, have a warm, smooth, sound while creating space with the B1 module. In comparison the Solar are a bit cleaner and a bit more detailed sound out of the box. The U12 requires some getting used to in order to appreciate just what all is going on. If you dedicate the time you WILL be rewarded handsomely!
Treble is delivered differently than any other IEM I have heard. It is certainly not the focus. It is restrained and included as part of the rest of the mix. It extends and is not lacking and not rolled off. It is just blended into the mix which creates an illusion that the treble is neutered. This one aspect has taken me the longest to grow accustomed to. It is a bit of a strange sound signature that had to grow on me longer than any IEM I have heard. They are so smooth, warm and never fatiguing. Never any sibilance or harshness. I can listen not fatigued for hours. In comparison I feel the Solar offers a more balanced sound and is clearly more sparkly than the U12. If you need a more sparkly treble I would say the Solar would be more to your liking.

I have spent quite a few hours of listening to the U12 in a short time already. After the initial listen and growing accustomed to them the U12 has really become an incredible sounding IEM. They are a very musical with a great tonality. The sub bass rumbles as well as is clear and defined in the other ranges. The mids offer a great deal of clarity and are very detailed while the treble is skillfully blended in the mix.

I have listened to many genres of music with them, from Jazz, Blues, Classic Rock, Alternative. Streaming on the Pixel or listening to HQ quality on the Cayin i5 the quality is excellent.

Overall a warm(good warm), detailed presentation. It delivers an experience that you can listen to for hours without fatigue.

On a final note...You will be rewarded if you have the patience and allow your brain to adapt to the presentation. These are incredible sounding and have become my go to IEM. Will this IEM cure my addiction to this hobby and allow me to say end game achieved, maybe, but what would I do with my time or money?
Buy Them!!!!
EDIT:  Since the review I have purchased an OPUS #2 and the fact that the DAP is more neutral and has a balanced output has taken these IEM's to a sublime level. The majority of the congestion is gone and more details are shining through. These really shine with a DAP with a more neutral signature.

You and I are frightfully similar. We should stop resisting fate and just move in together. Your review echoes my own thoughts on the U12 completely, and its comparison to both Solar and Angie.

A less bessy DAP will also help balance these amazing IEMs. I found i5 a bit too congested with U12, but my AK120ii worked much better. Also, the Opus #1 gives a nicer pairing. I'm willing to bet the new X5iii will be more neutral still, giving the U12 a signature to really shine with.
Lol. When I thought I was letting this hobby go I sold my AK120ii ...foolishly. The Cayin i5 has opened up quite a bit.  I will say that the i5 powers the HD650 very well and adds only a hint of warmth. It is a very powerful dap that pairs better than my AK did with the Meze 99 Classics, that pairing is WOW. The X5iii is on my radar so we will see.


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