Disclaimer

I am neither being paid nor affiliated with 64Audio or Jaben Indonesia. This unit is generously loaned to me by Jaben Indonesia, as a compensation due to my CIEM order from a different brand being delayed.


Introduction

Due to an unexpected delay with my order, Jaben Jakarta kindly offered me an IEM to use while I wait for my order to arrive. Long story short, they loaned me their U10 demo for more than a month and I am posting this review today just after I returned the unit. I would like to thank the crew of Jaben Jakarta for their kind gesture.


Specifications



Hardware Build and Comfort


The unit has a transparent shell made with acrylic, with solid build quality. On the bottom of the faceplate, there is a slot for you to use your APEX or ADEL module. It is also lightly decorated with the company logo on the left unit while the right unit has the number 10 printed. At the back of the unit, the serial number is embossed in a small font, providing a clear look on the configurations of drivers inside. The size of this IEM is very small, there are many other IEMS with fewer driver count yet still having a larger footprint. Please note that the unit that I am reviewing is a demo, therefore it might not provide a true representation of the U10’s production version.


Together with the stock cable, the U10 was also loaned to me with the Apex M20 units installed and a pair of silicone tips. The cable has a memory wire but it doesn't add much to its thickness. They feel comfortable to use with my glasses on despite having some microphonic issue. The silicone tips are nice and has a good seal, providing a good amount of noise isolation.



Source

Sony Z5 phone
Questyle CMA400i DAC with Headphone Amp

The U10 is not too picky with its source, they are the kind of phones that will scale depending on what they are paired with. With my phone the U10 sounds warm and musical but hisses a little bit. After plugging it into the CMA400i, it sounds airier and have much better technicality overall.


Sound

Despite only having assigned 2 drivers, the U10 still has a good rumble and punch. Even though it is accentuated, the bass won't present itself until the song asks for it, and they do it with a good ability of hitting it deep and tight.

For the midrange, the U10 sounds relatively smooth and are a little bit laid back. Its lower midrange are just slightly more pronounced than the upper mid. Unfortunately due to its laidback nature, it is not rare that they got congested by the lower ends. Furthermore, there is a slight bit of sibilance, especially noticeable on poorly mastered tracks.

Tuned for a reference sound in mind, their treble have a proper extension and a good amount of presence. The treble have a smooth non fatiguing sound with a tad fast decay. Due to its slightly more forward nature than the midrange, the U10 also has a good resolution and decent transparency.

The whole package sounds good, and even though they are a little bit revealing, I don't consider them to have a reference tuning. They are neither analytical nor neutral, and personally I find the U10 as a laid back phone with a slight v-shaped character. The soundstage on this IEM are airy and wide with a decent depth and height. On the other hand, separation and layering could be better, but it still has a good enough clarity and resolution to capture micro details. I assume as a result of this tuning, the timbre is slightly off which is noticeable on tracks where multiple instruments are playing.


Conclusion

This IEM sounds great no matter whether if the source is good or bad; and because of its signature, they also go well with many genres too. With its small size and a relatively thin cable, comfort is not an issue if you get yourself a good pair of tips. However, the main downside of the U10 is that they don't have any particular strength even though they do well on most conditions. And with a MSRP of $1399, it is difficult to recommend this phone unless you are specifically looking for a mild v-shaped UIEM with a good dose of non-fatiguing treble.


P.S. - Comparison based on memory (Please read this with a substantial grain of salt)

FitEar MH334 (CIEM demo) - The 334 has a reversed v shaped signature. Midrange are more pronounced and timbre is more accurate on the 334, while the treble have more authority on the U10. The U10 have a smaller soundstage than the 334, with poorer imaging but equal detail retrieval.

Custom Art Harmony 8.2 (CIEM demo) - The 8.2 sounds warmer, less treble presence and more coherent than the U10.

Ultimate Ears 18+ Pro To Go - The 18+ sounds leaner with more accurate timbre but there is very little upper end presence compared with the U10.

Noble Kaiser Encore Universal - The Encore bass is less authoritative, while treble are brighter and has better extension than the U10. Soundstage are bigger on the Encore and overall they have a better resolution and detail retrieval than the U10.

Aroma Witch Girl Pro Universal - The Witch Girl Pro have a well pronounced low end and a more reserved mid and upper range versus the U10.

INTRODUCTION

A fair bit of this review may borrow sections from my U6 review. The reason for this is that a lot of the prelim stuff is the same. I can assure anyone reading though, that I went through exactly the same comprehensive testing procedures I always do.

The U10 was very generously provided by 64Audio so that I could do a follow up review and comparison to my U6 (which I bought and paid for as part of the original Kickstarter). And I'd just like to thank Vitaliy and his team from 64Audio for giving me this opportunity. I'd always questioned from the first time I heard the U6 – whether I should have spent a little extra on the U10, and if I had missed out on the fabled “audio nirvana” because I didn't have the funds at the time. Thankfully I've now answered that question for myself, and I am indebted to 64Audio for giving me this chance.

I want to cover a few things before we get to the review proper, so please bear with me.

• Most of the history/preamble section is to do with the reasons why I first looked into 64Audio and Asius. I've spoilered it so that those who've already read it in my U6 review don't need to go there again. There is some personal background in there, and the answer to the “why” I bought the U6 – if you haven't read it, it should give you some real insight behind my purchasing decisions which is very pertinent to the U10 also.
  
  
• As many people will realise by now, 64Audio and Asius have decided to part ways. I want to make it clear that I am simply a neutral observer, and I'm not taking any “sides”. I've spent some time with Vitaliy and his team (including an RMA – we'll discuss in the “service” section), and I've spent a few hours with Stephen and Steve from Asius – including being involved in a Spree video-cast. Both companies have my admiration for what they can do with these tiny audio devices. Vitaliy's tuning is magical (especially once you learn a few secret tweaks), and Stephen's technology with Asius has actually changed my “audio life” - and I'm sure it will have a marked effect on preserving my hearing. I wish the collaboration had continued – sadly it didn't – but life goes on. The important thing is that I wish them both well in future endeavours.
  
  
• My comments in relation to the Apex modules vs Adel modules are my own personal experience, and are 100% honest. I want to stress this – because if the results had been reversed, I would have reported that. In this review (and for any others I write), it is far more important to me to write my actual experiences.
  

History / Preamble
Discovering 64 & Adel

ABOUT 1964 EARS / 64Audio
1964 Ears was started by Vitaliy Belonozhko, a sound engineer who has been working with musicians and production companies in the Northwest for more than a decade. Not long into his career he discovered the advantages of IEMs over traditional floor "wedges”. After trying out a few brands it was apparent to him that a better and a more affordable solution to in-ear monitoring was needed, and 1964 Ears was formed in 2009.

Why “1964”? Because to Vitaliy that was a breakthrough year – both in terms of some landmarks occurring in music (Stones, Beach Boys, Dylan), but also because it was the birth of the first In-Ear Monitor by Stephen Ambrose. Since then Vitaliy and his team have been producing, refining, and developing both custom and universal monitors for both musicians in the industry and also for ordinary consumers. Recently 1964 Ears was shortened to the now familiar 64Audio we see today.

I pulled the next bit straight form the website, and I think it sums up 64Audio quite nicely:

Everything about that special year (1964) was life changing, and it left an indelible mark on everyone who lived it or later learned of it. 64Audio’s sole focus is making that same mark when it comes to personal audio. It was Syd Moore who once said, “disregard for the past will never do us any good. Without it we cannot know truly who we are”.

We know who we are.

ABOUT ASIUS TECHNOLOGY / STEPHEN AMBROSE
Fifty years ago, Stephen Ambrose invented the world's first wireless In-Ear Monitor technology (IEMs). Already a professional musician at age 12, he began modifying swimmer's earplugs with tiny speakers and clay and completed his first In-Ear Monitor in 1965. This was the first time full spectrum high fidelity sound was delivered within a fully sealed ear canal by an In-Ear Monitor. Touring for decades with hundreds of performers including Stevie Wonder, Simon & Garfunkel, Diana Ross, Rush, Steve Miller, Kiss and many others, Stephen was able to perfect and commercialize his IEM designs and was the sole provider of in-ear monitors to the professional market for well over a decade.

Greatly concerned over the increased risk of hearing loss due to the use of personal listening devices, Stephen began extensive research with grants from the NSF and NIH and pioneered new scientific discovery into hearing loss (specifically from the use of IEMs). To solve the problem, he invented and patented a revolutionary “second eardrum" called the Ambrose Diaphonic Ear Lens (ADEL™) which absorbs harmful in-ear pressures.

In early 2014, Asius and 1964 EARS, joined to design and manufacturer the 1964ADEL line of earphones.

A NOTE ON SERVICE – 64AUDIO AND ASIUS
One of the things I've learned with audio, and especially since becoming more popular with my reviews, has been that manufacturers make mistakes, components are not always perfect, and no matter how good a company is, products can have defects. The measure of the company is how they deal with those situations. I want to mention this specifically so I can give you a feel for my own experiences with both 64Audio and Asius.

When I ordered the U6, I realised there would be a wait, and because I was travelling to the US, I tried to arrange with 64Audio to pick up my U6 from friends in the US. Unfortunately I missed the window for the delivery, but 64Audio made sure they arrived, and my colleagues forwarded them to me. When it came to the case (being sent later) – it was lost in transit, so I exchanged a couple of emails with Alex at 64Audio, they checked the situation out, and we arranged a replacement. At around the same time I had a cable fault with one of the connectors, sent them a photo, and they arranged immediate replacement. I actually sent the faulty cable back so they could check it out – but I wasn't obliged to do this. 64Audio were impeccable in their communication, they arranged the replacements, and at no stage did they make onerous demands. They simply wanted to make sure that I was happy with the product – and I am. That is great service. In addition, a few months ago I had a driver die in the U6. The RMA was completely painless, fantastic communication throughout, and the result (repaired U6) was great. 64Audio (in my experience) are very good with customer service.

I could also say the same about Steve and Stephen at Asius. With the first trial MAM unit, when testing I over-rotated the dial and broke one of the modules. No recriminations, they just wanted to know how it happened (so they could correct it for subsequent models), and they wanted to get me replacements as soon as possible so that my experience with them was up to my (and their) expectations. I also wanted to know more about the tech, so they've made themselves available, taken their time to listen, explain, and gone out of their way to ensure the explanations are being understood. Since then I've skyped them a couple of times, and assisted with a Spree-cast.

Both companies are passionate about what they are doing, but more importantly they care about their customers. And that to me is both reassuring and very refreshing.

DISCLAIMER
The 64Audio Adel U10 I am reviewing today is a loaner provided by 64Audio for the purposes of review. Following the review I will (with genuine regret but profound thanks) ship them back to 64Audio. I have no other affiliation with either 64Audio or Asius other than being an owner of their products (U6 and various Asius Adel modules). There is no financial incentive in writing this review.

The 64Audio U10 I am reviewing today can be currently purchased from 64Audio's website for USD 1399.

PREAMBLE - 'ABOUT ME'.
I've now had the 64Audio U10 for around a month, and in the time I've had it, I've used it with practically all the sources at my disposal – including FiiO's X3ii, X5ii, X7 (AM1, AM2, AM2A, AM3 & AM5), L&P's LP5, L5 Pro and L3, my iPhone 5S, and also most of my portable and desktop sources. In the time I've had the U10, the only changes I've observed have been adjusting to the different modules, use of impedance adaptors, and also slowly becoming more used to the U10's default signature. I've noticed no “burn-in”, and testing with different amplifiers has not revealed any marked sonic improvements when blind tested (the U10 is relatively low impedance and high sensitivity, and IMO requires no further amping with a decent source).

This is a purely subjective review - my gear, my ears, and my experience. Please take it all with a grain of salt - especially if it does not match your own experience.

THE REVIEW

PACKAGING AND ACCESSORIES
When the U10 arrived, being a demo unit, it was just with the custom 64Audio Adel series 3D printed hard case. Rather than give an incomplete picture of the accessories you'll receive, I've simply taken some of the photos from my U6 as I know the accessories are practically the same.


The default package you'll get is:

1. The U10
2. New 64Audio 3D printed case
3. 1.2m detachable cable
4. Comply ear-tips in S, M, L
5. Cleaning tool
6. Dehumidifier (for the case)
7. Apex auto module (likely to be the M20)

Normally if I'm given a case the size of the 64Audio 3D printed case, I'd never use it – too big to carry around. But I use my own 64Audio case all the time despite it's size. The case is totally 3D printed and measures a fairly hefty 115 x 70 x 35mm (excluding clasp and hinge). It's more like a smallish pelican case. It has the 64Audio logo embossed on the top. It is very hard, very solid plastic, and should do an extremely good job of protecting your investment.


Inside (top cover) is a place to hold two extra sets of modules, a shirt clip, and cleaning tool. The moulds don't currently fit the Apex models which are slightly narrower – but I'm assuming they'll fix these pretty soon. The module holders are brilliant if you're using the Adel modules though. I now have the MAM, B1, S1 and G1 modules, so I have a place for 1 set (fitted) and two spares. There is also a soft piece of foam strategically placed on the top lid to fit over the compartment holding the U10.


The bottom section has a split compartment to house both ear-pieces. Each of these has a slit (for the cable). Inside is actually a rubber holder to ensure there are no hard edges putting pressure on the IEMs. The cables then run to a split T pole arrangement so that you can wind the cable around. Situated around the pole are 4 raised slots for the 3.5mm jack. So no matter how you end up winding, you have a handy slot to inset the jack, and secure the cable. The whole set-up takes very little time to pack or unpack, is very protective, and just really well thought out. The icing on the top is in the clasp itself, and also in the case (its not evident until you actually look closely). The top cover has a small ridge around the rim. The bottom of the case has a small recess/groove. When the case is closed, it is essentially air-proof/moisture proof. To assist with the pressure of opening or closing, the clasp houses a small pressure manual valve. It opens when the clasp is pulled open, and engages when it is snapped shut. Really clever.

I could not ask for much more regarding the included accessories. Some may miss a 3.5-6.3mm adaptor or an airline adaptor – but most of us already have spares – so I don't regard this as an oversight at all.

TECHNICAL SPECIFICATIONS
(From 64Audio's website)

I’ve listed the main specifications for the 64Audio U10 below, and also (for comparison) my own U6.


FREQUENCY GRAPH
The graphs below are generated using the Vibro Veritas coupler and ARTA software. Ken Ball (ALO/Campfire) graciously provided me with measurement data which I have used to recalibrate my Veritas so that it mimics an IEC 711 measurement standard (Ken uses two separate BK ear simulators, we measured the same set of IEMs, and I built my calibration curve from shared data). I do not claim that this data is 100% accurate, but it is very consistent, and is as close as I can get to the IEC 711 standard on my budget. If you compare to older measurements I've taken (in older reviews), please take into account that my new calibration is different (much more accurate).

In the graph below – you’ll see the frequency plot for the base sound of the U10 with the Apex module. Later in the review I'll also show measurements taken with other modules.



What I’m hearing (subjective) – noted before I ever had these on the measurement bench.

1. Pretty good bass response – elevated compared to mid-range and pretty well extended. The bass is quick and well textured.
   
2. Very clean and relatively coherent mid-range which to me slightly favours the lower mids, and is a bit gentle in the upper mid-range around the presence area (2-3 kHz) which I am particularly sensitive to. So for me this flattens the transition between lower and upper mid-range, and female vocalists lose a bit of euphony. Has a tendency to sound flat to me. Note – this can be corrected via pairing with a higher impedance source (or use of an impedance adaptor) – we'll cover this later.
   
3. Reasonably extended but quite smooth lower treble which falls short of excessive sibilance (for me) yet remains detailed with some air for clarity. Lower treble tends to sound a little rolled off compared to 64Audio's U6.
   

BUILD & DESIGN
Similar to when I first saw the 64Audio Adel U6, I'm surprised (incredulous actually) that the U10 isn't a lot bigger. Ten drivers into a tiny shell, and managing to keep the housing both ergonomic and comfortable to wear – 64Audio has done a wonderful job here. The earphone casing might look shiny and a bit plasticy, but the shell is actually a hypo-allergenic hard acrylic. I've now had the U6 for almost a year with zero issues with the shell, so the U10 should stand up as well. The U6 measures 22mm across, is 18mm tall (from the cable exit to bottom of the shell), and approx 9mm deep (main housing). The shell itself is seamless, and there are no ports. The inner face is smooth and rounded and extremely comfortable to wear, with no sharp edges or protrusion.


The nozzle protrudes from the inner face by 14-15mm, and is angled upward. The actual nozzle piece itself is 9mm, has a very slightly raised ridge for tip retention (no real lip), is quad bore and is approx. 5mm in diameter. Normally I'd be pretty grumpy not having a lip – but because of the generous length, and the slight ridge, I've had no issues with my preferred tips coming off.

The outside face is smooth and flat, and very simply printed with “10” on the right earpiece and “64 Audio” on the left I nicely contrasting white print. At the forward apex of the front face, directly opposite the nozzle, is the hole for the Adel or Apex modules. This is 6mm in diameter, and if you blow through it (with no module), you can clearly feel your breath on the other side – it essentially opens a hollow conduit from the outer face to inner face.


At the top of the body is the 2 pin socket for the removable cable. On the U10, the cable is not recessed, but the connection seems pretty sturdy to me. The cable is 1.2m long, has approx 6cm of memory wire, and consists of two sets of twisted pairs (one from each earpiece), which stay separate from earpiece to jack through the entire cable length. This is perfect for anyone wanting to re-terminate to balanced. The Y-split is just simple heat-shrink (with a clear piece of plastic above it for a cinch), and below it the two twisted pairs join to become a twisted sprung quad cable. The jack is gold plated, right angled, and has excellent strain relief.

I cannot fault a single part of the build or design at this point – it really is pretty impeccable.

FIT / COMFORT / ISOLATION
The shells are very smooth, beautifully rounded, and basically disappear for me when worn. What is better is the extra length of the nozzle and also the angle because it means I can get a more secure seal, and with a wide variety of tips.


So far, I've been able to fit and use successfully – the default Comply tips, Spin-Fits, Sony Isolation tips, and even Shures standard tips (takes some stretching but they do work). Ostry tips fit fairly shallow, and with no lip come off easily, as do Spiral Dots. There should be enough options to suit everyone, just know that without a lip on the nozzle, if you have a shallow fitting tip, it may become lodged in your ear.

Worn over ear the U10 sits well inside my outer ear, so lying down and listening is never an issue, and I’ve been able to sleep with them intact. Cable noise worn over ear is very slightly microphonic if the cable is worn loose, but cinched or tucked under clothes it is amazingly silent.


Isolation is advertised as -20 dB for the Apex M20 module. I was asked to do a test (by PM) with my U6 involving listening with the S1 module with 80 dB background noise – so I simulated it with a youtube video and my monitors measuring room noise at an average of 80dB. I repeated this test with the U10 and similar to the U6 you could pretty clearly still hear the ambient noise (dulled but still present). Playing music and the background noise becomes a much quieter hum. I probably still wouldn't use these for air travel – but they provide enough isolation for use in a semi-noisy environment (and no issues with office etc).

So for me anyway – fit and comfort are pretty close to perfection again. Isolation will depend on tips, seal and which module is being used.

THE MODULES (APEX AND ADEL)
The new Apex M20 module is both similar and quite different to the S1 it was modelled on. Externally it is within 1mm of the same height, and very slightly smaller in diameter (less than 1mm total). If fits nicely into the U10 socket – but definitely not with as much “grip” as the Adel modules – it is secure though (the two rubber rings ensure this). The other major external difference is that the vent is no longer on the top but inside a small groove on the side. This change cuts down on the wind noise quite a bit and is a great bit of innovation if you're wearing them outside. Good job 64Audio. Internally they are extremely different. Where Asius uses the patented Adel (Ambrose Diaphonic Ear Lens) inside their modules, which acts as a pressure valve to absorb the dangerous pneumatic pressures, the Apex module uses a multi-cell thermoplastic alastomer (TPE) which acts as a damper – and it is that combined with the vent which allows them to “mitigate pneumatic pressure”. Unfortunately my own real world testing shows that for me it does not work as well as the Asius modules in terms of relief of my tinnitus, or other associated hearing fatigue indicators. More on that shortly.



THE ADEL TECH (in layman’s terms – from my U6 review)
I thought I’d attempt to explain very briefly my understanding of the ADEL tech, and what it is supposed to do. I’ll also explain how it has changed the way I listen.

When we use an inner ear monitor, we do things that are very different from listening to open headphones or speakers. Firstly we close and seal the canals, and Stephen’s research has indicated that this leads to a couple of issues. By sealing the ear canals, we actually turn our heads into a big amplifier. If this sounds weird, try doing any exercise (to get your heart beating), and then plug your ears, listen and then unplug your ears again. Yep – you’ve just amplified things enough to hear your internal body functions. On top of that, when we seal the ears, and play sound directly into them, Stephen has been able to deduce (in frequency vs phase tests) that not only are the sound waves amplified, but we also create pneumatic pressure. Our ears have an inbuilt defence mechanism called the acoustic reflex which works really well to dampen loud sounds so that we don’t feel the full force. But typically what has been happening is that in listening to IEMs, we are triggering that acoustic reflex early, which is dampening the sound, so we turn the volume up, which further triggers the acoustic reflex – and the cycle continues until the reflex is overwhelmed, and we are putting sound waves at dangerous levels into our inner ears, and hearing damage ensues. The other side effect of dampening the sound is that when the mechanism is triggered, our ear drums are pulled tauter, and results in degradation of sound.

So can this be fixed? Enter the ADEL technology. What ADEL does is provide a membrane which absorbs some pneumatic pressures so that the acoustic reflex is not triggered too early. As a result we get to a safe listening level at far lower volumes. And without the damping effect, the sound should also be much cleaner, and more like listening to open cans or speakers. A side note though – if you listen loud, ADEL will not be able to stop you damaging your hearing. Some user sensibility is essential.

But let’s take a look at my own situation. I use IEMs a lot. I also suffer from permanent tinnitus. I’ve trained myself to listen to music a lot quieter over the last 10 years or so – and my average listening level (depending on environment) would be around the 65-75 dB mark. Even though I do listen relatively quietly, I have noticed that wearing IEMs for a long time still tends to irritate my tinnitus (causes it to flare up or intensify), and I’ve always worried that I may be causing further damage.

Since getting the ADEL modules and U6, I’ve noticed that my measured listening level is more in the 65-70 dB level with the U6, than in the 70-75 dB. And when I volume match at my normal listening levels, and then listen at the same dB level – the U6 tends to sound slightly louder to me. The other thing I’ve noticed is that with the U6 I am often lowering the volume rather than raising it. With my other IEMs, it is often the other way around. I've also noticed that my tinnitus stays a lot better behaved – even after extended use. I know a lot of things can affect it – but I do believe the U6 with ADEL technology is helping.

For me the differences aren’t huge (in SPL) but at low listening levels, the U6 simply sounds clearer. I know this is anecdotal, but it is genuinely what I am noticing. Your own mileage may vary. For resource to look further into ADEL, I recommend the following:

Asius website : https://asiustechnologies.com/tech
Recent spreecast : http://www.spreecast.com/events/n64-audio-adel-discussion--2
Kickstarter website : https://www.kickstarter.com/project...gy-that-saves-your-hearing-and-yo/description

Again – I have no affiliation with Asius, and can only tell you what I am experiencing.

THE DIFFERENCE
I'm trying to lose some weight (Brooko has got pudgy again). So recently I've been doing more walking, and this usually means 1-2 hour walks daily (depending on available time). The nice thing about both Apex and Adel is that the venting allows the earphones to be a lot more open – so you don't get a lot of bone conduction (ie that pounding sound when you are walking/jogging). Again – when you fully seal your ears, your head acts as an amplifier – so you hear a lot more internally. Both the U10 with Apex and U6 with Adel are a lot easier on your ears when exercising. But using the U10 for the last few weeks, I started to notice when I was walking, that after an hour my tinnitus would start to flare up (the ringing gets louder). I also noticed that I had more of a tendency to turn the U10 up with Apex – which I know is a sign that the acoustic reflex is being triggered. The last sign was after the exercise when sometimes it would sound as though an ear was partially blocked (basically it feels like occlusion). I know this to be a sign of my ear fatiguing. After a while it goes away.

So I used the U6 for the next couple of days and the effects mentioned disappeared. Went back to the U10 with Apex, and the symptoms returned again. Finally I went with U10 and B1 module, and symptoms gone.

I really like the design of the Apex module, I really like the tuning – but as a tinnitus sufferer, and with the main reason for buying my U6 being the acoustic and health benefits, I'm afraid I'm going to just have to say that after my experience I'll be sticking with the Adel modules. I'll be interested to see if anyone experiences the same things I have.

MODULES AND MEASUREMENTS
This will be quite a big section – and sorry for all the graphs – but there is no other way to do it. What I'm aiming to do here is to give you measurements of the U10 and also the U6 with different modules, and show you the differences. I'm not going to cover the MAM this time – if you'd like to see what it does, I'd suggest reading my original U6 review.

Impedance Adaptors
One of the things which has been revealed relatively recently is that some of the 64Audio IEMs were tuned with a source with a relatively high (up to 20 ohm) output impedance. This of course is because many of them were designed as stage monitors, and the wireless packs tend to have higher OI. Of course this doesn't help many of us with extremely low impedance sources – and by using these, we're actually not hearing the true tuning. With lower impedance, we're generally getting a tilt upward in the bass, and downward in the upper mid-range. This makes some of the IEMs both warmer and smoother (which explains a lot with me trying to EQ the U6 originally). One of the ways you can correct the frequency response is by using an impedance adaptor. I will (in the following graphs) show the effects of increasing impedance – and if you want a bit less bass and a little more brightness, how it can be achieved with an adaptor.

My measurement set-up
I use a Vibro Veritas coupler, cheapish Startech sound-card (which works pretty well for measuring IEMs), FiiO E11K amplifier (clean, linear, and with a < 0.2 ohm output impedance). The IEMs were measured with Crystal foam tips (they give me really consistent measurements which can be repeated and are consistent even months later). Software used is the ARTA measurement system

Thanks to Ken Ball (ALO Audio / Campfire Audio) I've been able to get his full measurements of a pair of Novas which I was then able to measure myself. His system uses two separate BK measurement systems (with ear simulators) which measure to an IEC 711 standard. I've used his profiles to build a calibration curve so that mine now mimics the IEC 711 standard. It won't be 100% accurate but will be miles more accurate than the original Veritas recordings were (the calibration solves the issues with readings above 4 kHz).

What I've measured

1. I've remeasured the U6, measured the U10, and compared the two
   
2. Measurements were with the Adel B1, and G1, and the new Apex M20 modules
   
3. I also repeated the measurements - but using a 75 ohm impedance plug to look at the frequency changes as described by Chris and Videl from 64Audio.
   
4. I chose not to include the S1 modules, as mine are measuring very close to the B1, and I suspect they may have undergone some change over time. This does not worry me – as its like having a spare set of B1's (which are my go to modules most of the time)
   
5. With the MAM – I only chose to show it measured closed as my particular MAM shows a plot almost exactly the same as the Apex M20.
   
   

U6 Graphs

U6 with all filters - interestingly, the Apex M20 has the most bass, and very closely mimics a closed MAM. The new G1 very closely mimics a fully open MAM.


Here is the U6 with B1 module (dark blue), and then the same module with a 75 ohm impedance adaptor (lower light blue line). The green line is volume matched (18 dB volume added) so you can see the effect of the adaptor (again lowers the bass, and gives a small bump to the mid-range)


Here is the U6 with new Asius G1 module (red), and then the same module with a 75 ohm impedance adaptor (lower pink line). The green line is volume matched (18 dB volume added) so you can see the effect of the adaptor (again lowers the bass, and gives an extra bump to the mid-range)


And here is the U6 with new Apex M20 module (orange), and then the same module with a 75 ohm impedance adaptor (lower pink line). The green line is volume matched (18 dB volume added) so you can see the effect of the adaptor (once again lowers the bass, and gives an extra bump to the mid-range)

U10 Graphs

U10 with all filters - interestingly, the Apex M20 has the most bass, and very closely mimics a closed MAM. The new G1 very closely mimics a fully open MAM.


Here is the U10 with B1 module (dark blue), and then the same module with a 75 ohm impedance adaptor (lower light blue line). The green line is volume matched (19 dB volume added) so you can see the effect of the adaptor (again lowers the bass, and gives a small bump to the mid-range)


Here is the U10 with new Asius G1 module (red), and then the same module with a 75 ohm impedance adaptor (lower pink line). The green line is volume matched (19 dB volume added) so you can see the effect of the adaptor (again lowers the bass, and gives an extra bump to the mid-range)


And here is the U10 with new Apex M20 module (orange), and then the same module with a 75 ohm impedance adaptor (lower pink line). The green line is volume matched (19 dB volume added) so you can see the effect of the adaptor (once again lowers the bass, and gives an extra bump to the mid-range)


And here is the Apex M20 vs my MAM fully closed.


My personal pick of the modules which best suit me for tuning alone would be the Apex M20 + impedance adaptor for the U10, and Adel B1 + impedance adaptor for the U6.

SOUND QUALITY
The following is what I hear from the 64Audio U10. YMMV – and probably will – as my tastes are likely different to yours (read the preamble I gave earlier for a baseline). Most of the testing at this point (unless otherwise stated) was done with my FiiO X3ii and E17K, and large Comply T400 tips. For the record – on most tracks, the volume level on the E17K was around 15-16/60 on low gain which was giving me an average SPL of around 70 dB (mostly 65-75 dB) and peaks at around 75-80dB (A weighted measurements from my SPL meter).

Tracks used were across a variety of genres – and can be viewed in this list http://www.head-fi.org/a/brookos-test-tracks.

First Impressions
After spending a lot of time with the U6, I was expecting a bit more upper end (lower treble) energy, and maybe a bump in the upper-mids with the additional mid and high drivers of the U10. It was an area I initially thought the U6 lacked (before I got the MAMs and started playing with impedance). What surprised me was that comparatively the U10 (with the Apex M20) actually sounded a little warmer (dare I say darker) than the U6, and the lower treble response was more subdued and smoothed. It was pretty well extended – but it just wasn't what I was expecting. Over time I've come to recognise its strengths (especially once you introduce adaptors).

Relativities

1. Sub-bass – very well extended and there is good rumble there (which highlights the impressive extension), but bass is (IMO) too far elevated above the mid-range with the Apex M20 – and when you combine that with quite a flat mid-range things just tend to sound a little overly warm. Sub-bass is essentially flat compared to mid-bass – which then slopes down to the lower mids.
   
2. Mid-bass – elevated compared to mid-range, and has a traditional hump – but then remains extended through to sub-bass. Slight bleed into the mid-range, and because the mid-range is so flat, the mid and sub-bass can both dominate.
   
3. Lower mid-range – has very good body and is good with male vocals. But with any bass dominant music, vocals can sound just a little muffled or lost.
   
4. Upper mid-range – quite flat compared to lower-mids and only with a very slight peak at 3-4 kHz. I have to admit I was expecting a little more in this area, and if using the U10 without any added impedance, female vocalists can tend to sound emotionless. Not my favourite mid-range tuning.
   
5. Lower treble – extends well but at the same time is quite flat compared to the mid-range and actually recessed compared to the bass. Detail is definitely there – but can be softened or overly smoothed – especially compared to an earphone like the Andromeda – or even the U6. In it's default tuning (no adaptor), cymbals can lose their decay – especially if there is a lot of bass present (eg bass guitar)
   
   

Resolution / Detail / Clarity

1. Good with micro detail, and able to resolve finer details well – but I would have liked something with more lower treble emphasis
   
2. Cymbal hits are good but can be somewhat muted or smoothed. Decay can be covered if bass is dominant.
   
3. For a monitor where the tuning was meant to be at the brighter or clearer end of the spectrum, I was disappointed
   
   

Sound-stage, Imaging

1. Extremely good directional queues, and just outside the periphery of my head space with binaural tracks – so above average width and depth
   
2. Spherically presented stage – without uneven emphasis on width or depth. One of the better portrayals of sound-stage I've heard with an IEM. Note here – when used with the Adel modules the impression of width and depth is enhanced
   
3. Good sense of immersion both with applause section of “Dante's Prayer”, and also “Let it Rain”.
   

Strengths (with added impedance)

1. Can be tuned with different modules and also with the use of higher source impedance. When using an impedance adaptor with the U10 they really come to life.
   
2. Very good sense of space and nicely open portrayal.
   
3. Generally good with most genres – and able to handle male and female vocals equally well.
   
4. Fantastic sense of layering – instruments occupy their own space when the adaptor is used. This is one area the U10 manages to best the U6.
   

Weaknesses

1. Without the adaptor (increased impedance) the U10 can sound very flat and slightly lifeless
   
2. Treble extension (to me) is overshadowed by the bass, and is not quite emphasised enough
   
3. Apex M20 modules are tuned really well – but give up a little openness
   

AMPLIFICATION REQUIREMENTS
The U10 is not a hard load to drive, and amping hasn't shown me that I'm missing anything. With my iPhone 5S I only need around 30-35% volume for my listening level. The interesting thing here is that I can add the 75 ohm impedance adaptor and still use my iPhone 5S (this time at about 55-60% volume). I did test the U10 with the IMS HVA – but found it overly warm. Probably the best amp for my use was the E17K – and this was mostly so I could use the tone controls (bass down, treble up) – even a 2dB shift each way was enough to greatly improve the U10 to my tastes.


As far as different sources go – the U10 sounds pretty good with everything I tried, although I have to admit a particular fondness for the L&P L3 with jazz EQ setting. Its another setting which really brings them to life.

COMPARISONS
This was a relatively easy one to arrange this time – as I happened to have the Campfire Andromeda with me – so I could compare the two. I also pitted the U10 up against the U6 and also Fidue's Sirius. As always, this part is completely subjective – and as such my comparisons may not necessarily reflect anything except my own particular bias and physical traits.

U10 vs Fidue Sirius
Both IEMs are multi-driver – with the U10 being 10 BA and the Sirius a 5 driver hybrid. Both have extremely good overall build quality – but the Sirius pulls ahead on overall build with it's metal parts, high quality (but bulky) cable, and a pretty good accessory range. For me personally, the U10 wins fit and comfort. The Sirius has sharp edges on top, and I have big ears so the shells sit inside my outer airs. The U10 I can wear for hours.


Sonically they are very different with the U10 being somewhat warm, flat and smooth, where the Sirius having more of a V shape. You'll note on the graph that Sirius has two lines, but I think the truth lies somewhere in between – this is because the Sirius has an internal bass port, so bass response could differ depending one ear anatomy and fit. The Sirius is also very upper mid-centric, and has quite recessed lower mid-range, so whilst female vocals in particular sound quite ethereal, male vocals can tend to be a little unnaturally thin and distant. This is quite a hard one to call for me – because the Sirius is definitely clearer and cleaner – but also definitely more coloured. With the use of EQ and/or adjusting impedance, my preference would be the U10, but without it, I might just prefer the Sirius a little more.

U10 vs U6
As you can guess, build, accessories, fit and comfort are all evenly matched. So this comes down to sonic signature. And for my personal tastes, the U6 just does almost everything better than the U10.


I find with the U6 that I can just use the impedance adaptor and the sonic signature is practically perfect. With the U10, I can EQ it to get closer to my ideal signature – but ultimately I think its the very smooth treble which I just find hard to live with. Introducing the Adel modules to the U10 can help – and I actually enjoyed the MAMs quite a bit with the U10 – but whenever I switch from the U10 to the U6, there is simply the feeling of “ahhhhh – that is what was missing”. Its the lower treble elevation as well as extension. The one thing the U10 does better (and its noticeable) is the sense of depth or layering – I guess this is Vitaliy's work with the extra drivers. If I could get the U6 tuning with the U10 sense of separation and space – it would be a formidable combo. At least my question has been answered though. I am not missing anything by not going to the U10. For my tastes, the U6 is the sweet-spot.

U10 vs Andromeda
Finally the U10 is up against Campfires 5 driver Andromeda. In this match up, the Andromeda wins on overall build quality (although both are very well made). You can't go past the quality cable and metal build of the Andromeda. For fit and comfort its a close thing – but the U10 gets the slight nod. And of course the U10 has the ability to switch out modules for tuning tweaks.


But sonically the Andromeda has a tuning practically identical to the U6, and as I explained above it's signature suits me to the ground. Where the U10 feels it missing some clarity, and can be too warm or too smooth, the Andromeda is simply beautifully clean and clear. For a choice between the two, I would take the Andromeda – but ultimately if the choice was widened, I'd simply take the U6 with Adel modules, and have the best of all three (and also the cheapest!).

64AUDIO U10 – SUMMARY

Sorry for the long review – the U10 (because of the tech) needs to be explained fully, and there simply is now way of taking short-cuts.

The U10 by itself is a very good IEM with an excellent acrylic build, small form factor (for the number of drivers) and good accessory package. Fit is excellent and with the longer nozzle I have no issues getting a great seal, and with very good comfort as well. It has a very flat mid-range with decent extension at both ends, but too much bass and too little treble presence for my personal tastes. I'd like a bit more top end, and a slightly better transition between lower and upper mids.

The one area which brings improvement is using a higher impedance source, or an impedance adaptor. I'm still scratching my head as to why 64Audio released the U series this way – but I guess a lot of this can be attributed to their main business being stage monitors. Anyway – it's worth getting a cheap adaptor – especially if you're like me and find them overly warm and a little on the smooth side.

The new Apex M20 module is tuned and built really well – but unfortunately in my case I'm not getting the benefits of Adel - which helps reduce fatigue (my tinnitus is much better behaved), and allows me to listen at lower volumes without compromising music quality.

For anyone who likes a warmer and smoother presentation but with very good extension – then the U10 should definitely be on your list to try. Its a great IEM – but for my personal tastes the U6 has the better tuning.

UPDATE : I've revised these up 1/2 a point from my original scoring as over time I've come to appreciate their tuning more and more. 64Audio left these with me for comparative purposes and they really do have a signature which grows on you over time. Particularly with the G1 module, I find these thoroughly enjoyable - and although expensive they do justify their price (enough that I'm considering buying this pair!)

FINAL THANKS
I'd just like to take the opportunity to mention and Vitaliy, Alex and everyone at 64Audio. Thank you for the exemplary service, and allowing me the pleasure of the experience of your product. Absolutely no regrets with the U6, and very appreciative of the chance to compare the U10.