64 Audio U12

Hello, it’s me… the TOTL monitors!

PROS: driver coherency, resolution, spatial details, ADEL module.

CONS: additional cost of MAM tunable module, not for those craving revealing/analytical sound.

The product was provided to me free of charge for the review purpose in exchange for my honest opinion.

Manufacturer website: 64audio.


Over the last few years and many headphones I tested and reviewed, my focus was always on the sound, the driver config, the design, and the accessories.  There wasn’t anything else revolutionary to talk about, and it seems like every new design was just a different cooking recipe from a pool of the same ingredients.  Though I never had a chance to review the original 1964 Ears monitors, I have read a lot of positive feedback and saw them as an established name in custom and universal IEM market with a typical clientele of performing artists and audiophiles.  So why would they take a risk and partner up with one of the pioneers of in-ear monitor technology to re-invent the wheel?  It’s obvious that Vitaliy and his 1964 Ears family, including a number of his actual siblings, really believes in Stephen Ambrose and his Real Loud Technology (in a form of ADEL module) which became a staple of every custom and universal model introduced under a newly rebranded 64 Audio company name.

The convenience of digital audio format, portable audio players, and smartphones all together propelled the popularity of portable headphones.  While some still prefer the experience of listening to speakers when in a car or in a living room, the improvements in headphones sound quality made a lot of us realize that you can make speaker experience more personal, scaling it down to IEM level.  But that is also a double edge sword where you could be enjoying the music while damaging your hearing without even being aware of it.  As someone who used to listen to plenty of bass heavy music, I never questioned and actually welcomed the visceral low end rumble which only got intensified when I switched to the largest eartips for a better seal.  I didn’t know that in addition to a typical sound pressure, I was also experiencing a harmful effect of pneumatic pressure produced by the drivers.

Apparently, this pressure triggers an acoustic reflex, a mechanism that protects our ears from a loud sound.  Constant exposure to this pressure causes unnecessary triggering of this reflex which can wear it out and cause a permanent hearing damage.  Stephen’s Real Loud technology adds a release mechanism that allows this harmful pressure to escape, and this technology was encapsulated inside of ADEL module which stands for Ambrose Diaphonic Ear Lens.  More info about this could be found here: https://asiustechnologies.com/tech.

In reality a lot of us don’t want to be lectured with medical details or to be bothered reading about steps necessary to avoid hearing loss.  So have no worries, I’m done with my preaching!  After all, the main focus of this review is flagship TOTL 12xBA driver monitors, and I’m well aware that people are more interested about the sound and the effect of the ADEL technology relative to this sound.  But keep in mind, Vitaliy and his 64 Audio family teamed up with Stephen Ambrose to deliver not only the premium sound quality but also the design with ear health benefits.  Now, without a further ado, let’s proceed to the review.

Choosing the design.

I already mentioned this in a lot of my previous reviews, going with a custom fitment is a commitment on many levels.  You are guaranteed the best fitment made from in-ear impression taken by your local audiologist, you can customize the design to your liking with anything from shell color and finish to faceplate material, you eliminate the extra bulk of multi-driver universal shell sticking out of your ears, and also CIEMs guarantee to fit only you which deters others from “borrowing” it.  But at the same time, custom fitment requires longer waiting, you can run into issues requiring re-fitment, you can’t easily sell to upgrade to another model if you are not happy with a sound, and the shape of your ear canal can change over time.

I started my review with A12 based on impression that was on-file from awhile back and ended up with a re-fitment due to a weird shape of my left ear canal.  I actually feel that my ear canal fluctuates with weather changes and occasional sinuses where I’m at a mercy of a fitment which prevented me to start my proper review until I switched to universal U12.  With Universal you have to realize that fitment will heavily depend on a correct eartip selection which controls the seal and will affect the sound, especially the low end impact.  My choice of U12 over A12 was driven by my ear anatomy, but either selection will yield an identical driver configuration and sound tuning.  Overall, it’s a great business model where 64 Audio offers both Custom and Universal fitments in all of their 2-/3-/4-/5-/6-/8-/10-/12-driver designs.

With universal fitment you get an instant gratification of a pre-build model that will ship to you door within a week, but you also forfeit customization option, and it will be a generic compact black shell with a printed “64 Audio” on the left faceplate and “ADEL” on the right faceplate.  With custom A-model, the fun starts when you enter on-line DESIGNER tool.  You start with a model selection, where btw in addition to A2-A12 you can still find legacy 1964 Ears Q and V models.  In the middle of the screen you see a generic image of the shells where you can switch between Left/Right sides and see the cosmetic changes in real time.  The model selection screen also offers you a choice of a standard 48” cord or extended 64” variant, and a selection of either normal or a more secure recessed socket.  The socket itself is a standard universal 2-pin connector which you can use with any aftermarket cable, but be aware that some cables have connector housing that doesn’t fit recessed sockets.

On to a color selection, starting with a shell you only have 3 choices of either black, all clear transparent, or charcoal translucent.  Not as many choices in comparison to some other manufacturers, but you can compensate for lack of shell colors with a wide selection of faceplate colors, finishes, and premium material.  You get a few dozen colors in standard or glitter finish, or can go with 6 different premium material faceplates, or 6 wood finish faceplates.  Obviously, faceplate itself will not be exposed to outside and usually laminated by acrylic layer of the shell.  In addition to color selection, here 64 Audio also offers you a choice of cable color to match the shell.

Artwork tab will allow you customization of the logo where you can select from pre-defined ones in any of 7 colors, or to upload a custom artwork which has to be checked by 64 Audio to determine feasibility.  Before you proceed to the check out, you have an option to add your name on the case, specify name of the person wearing it, notify if this is a rush order, and also to mention if you are sending new impressions or allowing 64 Audio to use the one stored on file.

Once order is placed and you receive confirmation, 64 Audio offers something which I haven’t seen with any other manufacturer – a progress bar report which you can login to anytime to check the progress of CIEM manufacturing.  It will date each step of the manufacturing process and will provide you with a brief description of what they are working on.  It could feel dreadful when you have to sit and wait 4-6wks for your customs without knowing what’s going on.  Here, it makes the time go faster and you know exactly what they are working on.  Maybe 64 Audio doesn’t offer as many exotic colors or finishes, but they make up for it with a progress report tracking and excellent customer support.

Unboxing and Accessories.

The unboxing experience should be common for either custom or universal models.  Majority can probably relate to this where with CIEMs the number one priority is to check the fitment out of the box, but I had to take a pause after I removed the outside sleeve.  First of all, the packaging box itself is very compact – a dead giveaway that you are dealing with a custom case and not your typical Pelican box.  After you lift another cover you will find a printed Quick Start guide talking about putting earpieces in and paying a close attention to volume adjustment – a strong indicator that 64 Audio is very serious about a hearing health.  Inside of the box you will find a plastic rectangular storage case and a partitioning section with dehumidifier “tablet” commonly used with CIEMs to dry out the moisture accumulated in the nozzle.

With dimensions of about 120mm x 70mm x 35mm, the case is smaller than a typical CIEM Pelican box, but its “beauty” is on the inside, not the outside where I found 64 Audio logo and my “Twister6” faintly visible name.  This is a truly custom case with a level of partitioning like I have never seen before.  You have two separate deep sections for each earpiece with a rubber lining and a slit for a cable.  Then, you have a split core cable winder where you start off by pulling the cable from each earpiece through a split and then winding it around the outside.  When done, there are 4 vertical holes to park your headphone jack, whichever closer for the reach.  Obviously, this is more appropriate for a right angle headphone jack, but I had no issues with a straight connector and my heavy aftermarket cable – there was plenty of room for everything.

Between the earpiece pockets and the cable winder, you have a small round area to hold securely the “dehumidifier” piece.  The cover of the case has a soft lining right above the earpiece area so when you close it – earpieces won’t touch the plastic top.  Also in the middle you have a secure holder for a cleaning tool with a brush on one end and earwax remover on the other end, and another place to attach a shirt clip.  Both of these removable pieces fit secure and nothing will rattle or move loose as you carry this case.  There were also 4 pockets for 2 pairs of ADEL modules to keep your spare adjustable or auto-modules securely stored.  Also, underneath the latch you will find an air vent to release the pressure as you close the lid, sealing the vent when you engage the latch to close the case – keeping everything airtight and secure.



Case and accessories.



The included silver-color stock cable, arrived with A12 (U12 comes with a black cable), is one of the best looking 2-pin generic cables I have seen among the other reviewed IEMs/CIEMs, but at the same time I felt it doesn’t do A12/U12 justice.  As always, I strongly encourage people to wait with a cable upgrade until you spend more time getting to know the sound of your IEM/CIEM with a stock cable first.  Otherwise you will not be able to hear and to appreciate the benefit of the upgrade.

The stock cable definitely looks premium with a translucent right angled connector housing and a nice strain relief where you get a clear view of soldered wires on the inside.  The cable has 4 braided conductors, 2 from each earpiece, where the L/R grounds are not joined until the headphone jack.  Y-splitter is a typical piece of a short shrink tube and chin slider is another clear piece that slides up/down.  The twisted pairs of the cable going to the shell connector have a memory wire, and connector itself has a standard universal 2pin jack and Red/Blue id dots to distinguish right/left sides.  Universal U12 comes with a standard black cable, but I’m sure you can request from 64 Audio a silver color replacement instead.

The stock cable is flexible, light, prone to microphonics, but I think part of it has to do with ADEL module/port since even with a decent isolation you are still well aware of surrounding environment.  Don’t expect earplug like isolation.  I tested it with a few of my other replacement cables that dead quite with other IEMs, and still hear some microphonics.  After awhile of using stock cable, analyzing A12/U12 sound signature, and picking up details of how it pairs up with different sources, I found that stock cable is great with bright sources but the neutral-warmish signature of this 64 Audio flagship becomes a little darker and smoother with warm sources, especially my smartphone.  This is purely a subjective opinion, but after cable upgrade I wasn’t able to go back to using stock cable.


I always find the subject of replacement cables to be controversial topic.  Some people either don’t hear the improvement or convince themselves there is no improvement without even trying a cable swap.  Others do hear the change but expect a significant improvement based on the price paid for the cable without realizing they’re dealing with diminishing returns.  I’m not here to argue with people, but rather to offer my impression based on what I hear with cables I have in my review possession.  There are a number of different aftermarket cable makers with products that could yield the same level of sound improvement, but I only have access to Linum and Whiplash cables, thus offer my opinion relative to these products.  Besides, Whiplash manufacturers cables in high volumes to distributors around the world, and it’s easy to find them even on Amazon.

Switching to Linum BaX makes cable completely disappear since their wires are super thin.   It also tightens the sound and brightens the tonality, especially in the treble region where I hear more sparkle after the upgrade.  But at the same time it pushed upper mids a little more back.  After closer listening, I determined that what I hear as mids being pushed back is actually a change in soundstage where depth has been improved but at expense of upper mids (especially when it comes to vocals) being pushed more back.  I wasn’t too crazy about this sound change.

Next I switched to Whiplash TWag and TWau cables, and that’s where the magic started to happen.  With TWag (pure silver conductors) the sound becomes tighter, bass is more articulate and with a better control, lower mids are a little cleaner and leaner, upper mids are still balanced but now a little bit sharper with improved retrieval of details, and treble is a little brighter, crispier, with improved definition and a little more airiness.  The holographic expansion of the soundstage is taken to another level with more width while still sounding realistic and not 3D-artificial.

Stepping up to TWau (gold plated pure silver), I hear a similar improvement where sound is tighter, bass is more articulate, especially a noticeable improvement in sub-bass texture, lower mids and upper mids improvement is similar to TWag but sound becomes a touch smoother and more analog while still being detailed and highly resolving.  Treble improvement is the same as TWag, and I hear the same soundstage width improvement.  If comparing TWau to TWag, I hear TWau adding a little more texture to the sub-bass, making mid-bass a touch less aggressive, balancing out upper mids by bringing them a little bit more upfront.  To my ears, both TWag and TWau introduce a noticeable improvement over the stock cable.

TWag with a standard 2pin connector and TWau with OM (over-mold) 2pin connector with spacer mod:



Since I had the opportunity to test both Custom A12 and Universal U12 replacement, I was able to capture a number of detailed photos and took plenty of comparison notes.  Obviously, it’s the same internal 3-way crossover design with 12x BA drivers partitioned in groups of 4 lows, 4 mids, and 4 highs.  Also, both are featuring a 4 bore design where 3 sound tubes from each group lead to the tip of the nozzle and a separate bore forms a return path to ADEL module.  In terms of a spec, both are rated with 16 ohm impedance, 115 dB sensitivity, and 10 Hz to 20 kHz frequency response implying low end extension.  Last but not least, both shell types use hypoallergenic hard acrylic material which is more common with Custom models, but also used in Universal one here as well.

As I mentioned before, Universal model is rather generic looking, all black with a long extended angled nozzle.   You don’t get a chance to see the internal arrangement of drivers, and there is no option to customize it, but the shape of the shell is very ergonomic and surprisingly not that big.  On the inner side the corners are all rounded and not for a second I felt uncomfortable wearing these for hours at a time.  Don’t expect to fall asleep wearing these with a head on the pillow, but they are lightweight and comfortable enough to disappear in your ear during extended use.  Of course, this is very subjective and also relative to individual ear anatomy, but as a reference – I wasn’t able to wear SE846 for more than 10-15min at a time due to their size, while U12 fits my average size ears like a glove.

There is no color coded L/R indicator, often found in other monitors with red on the right side and blue on the left side, and inside you will find etched U12 model number and S/N.  Since shells are not symmetrical, there is no way to mix up the fitment which always goes in one way with wire up.  On the outside, the faceplate has well defined corners and “ADEL” label on the right side and “64 Audio” on the left side.  Also, in the corner of the shell opposite of the nozzle you have a cylindrical cavity for removable ADEL module.  The location of the module is very convenient especially when you use MAM units to reach the adjustment crown with ease.  The nozzle is not too thick or too thin, has 4 evenly split bore quarters, and the body of the nozzle itself has a slightly thicker band in the middle with “12” label which helps to keep eartips from sliding off.

While U12 comes with a set of S/M/L Comply eartips, you are not limited to try whatever fits your the best.  Having a lot of different IEMs in my collection, I went through to find the most comfortable silicone tips which give me the best seal.  One thing to keep in mind during tip rolling (going through selection of different eartips), if you are playing with narrow bore tips like those found with Westone or Shure – you can stretch them to fit, but a narrow bore opening will cover the tip of U12 nozzle and it will definitely affect the sound.  If you want to keep the sound close to the intended signature, you need to select eartips that won’t obstruct the nozzle.

U12 Design.


U12 next to UM Maestro and Noble Savant.

U12 Fit.

Looking at A12 design is a whole different story.  Obviously, you are now in control of how the shell and the faceplate going to look, and able to clearly see the arrangement of drivers and crossover components through a transparent shell color I chose for A12.  So many times I used to wonder about other IEMs/CIEMs if they use dual or quad BA modules in order to fit such a small space inside of the shell.  Here, I was looking at a shell size which is on par or even smaller than some of my other 6-driver CIEMs, and yet I’m able to see 12 distinct drivers and a nice size tantalum capacitor and a small thick film resistor.  The room inside was fully utilized without wasting a single pocket of space, and that also included a relatively large cavity with ADEL module inside.

The workmanship of soldered wires interconnecting every driver and crossover components was impeccable.  I didn’t see any bubbles or imperfections; the shell looked great on the inside as much as on the outside where everything was smooth.  The model number and S/N were printed in red/blue colors to distinguish Right/Left sides – useful since CIEMs could be a bit confusing from the first look until you try to jam them in your ears (the difference is more obvious with universals).  The tip of the nozzle was smooth, rounded with 4 separate bores, including one going to ADEL module, and other 3 going to corresponding low/mid/high BA clusters.

Obviously, A12 model is based off a custom impression where 64 Audio scans it in and manipulates the trimming digitally.  If something doesn’t work, you have 30-day re-fitment grace period.  Once the shell is in your ears, the fitment is nearly flush without sticking out too much, though I wouldn’t recommend sleeping with these on.  Though I had a few fitment issues with A12, it has nothing to do with 64 Audio and rather a weird anatomy of my left ear canal where it starts off wide and then quickly turns and narrows down.  I’m quickly coming to a conclusion that Customs might not be my cup of tea, and I was very grateful for 64 Audio allowing me to continue with my review using Universal U12 replacement.

Design – A12


A12 next to Westone ES60.

A12 Fit.

Page 2: Adel modules, Sound analysis, Comparison, Pair up, and Conclusion. 

11 thoughts on “64 Audio U12

  1. hi twister,

    I want to buy aftermarket cable for my U12? Can you recommend which one should I buy which have best synergy with U12? Thanks.


      1. Hi, many thanks for your reply.. I tried to search the Alo ref8 but its difficult to send it to my country. Do you have alternative cable besides alo ref8 for U12?



      2. Ok with CB12 right? Not CB13.. I looked on their website only available with mmcx pin, so I need to reter again with 2 pin right? How far is the quality compare with alo ref8 since the price gap is big.



  2. Hi, the affinity is with angle 2 pin and not straight. is there going to be any problem fitting angle 2 pin with U12? I see the ref8 is also using angle 2pin.

    Please advise. Thanks.


    1. U12 is warm to begin with, so it just enhances its characteristics. Also, U12 is tuned for higher impedance sources. Adding impedance adapter can bring up treble more. Keep in mind, U12 is discontinued, they have U12t now, read my review on the blog. U12t uses Tia driver, it’s brighter and has a more vivid tuning.


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