Westone Elite Series ES60 - Reviews
Pros: Balanced sound between the lows, mids, and highs
Cons: Took a few tries to get the right fit and some cosmetic quality control issues. Quality control of the product is seriously flawed.
[UPDATE 2/27/2017]: 
So here's the update. Still sounds great. However, for various reasons (i.e. QC issues, fit issues, mmcx connector issues, dual-bore feature not done correctly, inconsistent techs finishing the IEM in different ways (e.g. rounded corners vs. sharp edge corners), and inconsistent transition of material from flex material and acrylic), I've had to return these monitors around 8 times already! 8 TIMES! They've been at the shop for more time than I have actually used them on stage! That's unbelievable!

I'm glad they spend the time to be very apologetic about these inconveniences. I just don't have all the time in the world to be packing, traveling, shipping, and waiting every single time just to find out that a few weeks later, there's going to be another problem with them. I have a couple of other pairs of custom IEMs and have not had to return them not even once (UEs and JHAs). 

I know Westone has a good reputation. But I really must have just gotten the lemon on this one. Either that, or their techs just don't care about quality. I'm hoping it's the former.

This last incident, I just got my monitors back from a warranty repair of faulty mmcx connectors and I open the package and find that the faceplate has a crack right down the middle. Should this be the type of quality to expect from a $1000+ pair of custom IEMs? 

I do stand with my previous statement that these are some of the best CIEMs I've heard. Though only ever so slightly better than my JHAs (I bought their most inexpensive model at the time). My UEs fit the best, at the time. Then my ears have changed which is why I bought these Westones. 

I have the Westone AC-20s as well which I use mainly for working out and those have been fine. But just to be safe, I will probably avoid Westone going forward. 

[Original Review]
I feel that because there are newer, flashier companies now making custom IEMs, people tend to forget the grandfather company that may have started the trend to the popularity of CIEMs. With that said, I only really have the UE CIEMs from 10 years ago to really compare these to. I can say, without a doubt that the sound and comfort level are much better on the Westone ES60s. But that doesn't say much as the UEs only have 2 drivers in each ear versus my new ones which have 6 drivers in each ear. So that's not really a fair fight. 

Where the big difference is in the fit. Though I admit that it took several tries of sending these IEMs back and forth just to get the fit right, I'm glad I sent them back as much as a did (including getting a re-mold of my left ear) because now they fit perfectly. It did cost a lot to send these back and forth. Where the Westones become really comfortable is that the ear canal portion of the IEMs have a flexcanal material. The canal portion becomes softer once your body heat heats it up and it makes for a very comfortable fit. 
Isolation is great. Design is great. Highs are slightly tapered which makes for a more relaxed sound which is what I like so that works out. Lows are prominent but not overpowering. Although, I bought these for casual listening, I think the sound is flat enough to suffice as being reference monitors. 

My next IEMs will most likely be a company located closer to home though (San Francisco) as sending the package back and forth proved to be way too annoying.

Again, the sound is great on these but customer service can be a little iffy sometimes. And it makes a huge difference which person is making them for you. I've found that being overly descriptive and getting on the phone with them helps them realize better what your requirements are. 
ES60 seems to be outdated but I think still it can be one of the best options today between many new top ciems.. Definitely shame that there is not much info comparison reviews about them. 
Pros: design combo w/acrylic and silicone, sound signature with a smooth reference quality (upgrade from W60), 6xBA drivers per side, customization level
Cons: price, CIEM fitment might not be for everybody

Before I start my write-up, I would like to Thank Westone for providing me with a review sample of their flagship ES60 CIEM in exchange for my honest opinion.
Product page: http://www.westoneaudio.com/index.php/products/custom-series/es60-in-ear-monitor.html
As I bonus, I will also cover in my review Westone new Ultra-thin balanced cable (THIS), and TRU hearing protection earplugs with a replaceable filter (THIS).
*** Since I was asked to find out what is a typical turn time to have ES60 done after Westone receives impression, I confirmed it to be 6 business days.

After my review of W60 UIEM and a follow up review of UM56 custom eartips, I received a number of questions asking me if W60+UM56 would be an equivalent of ES60 “custom” experience.  If you think about it, you are still dealing with the same 6 driver configuration and multistage crossover where drivers are partitioned in pairs of lows, mids, and highs.  The obvious difference in here is a shell design where instead of Westone signature universal bean shape, now you have a custom shaped mold based on your in-ear impression (taken by your local audiologist).  In theory they should sound close enough, but how about in practice?  After receiving ES60, I was very surprised by what I found, and now would like to share with you the results of my testing after 2 weeks of continuous use.
Before I start the review, let me take a step back to revisit W60.  Unique tuning of W60, along with my “unique” ear anatomy, made this IEM rather sensitive to eartip selection which drastically affected the sound.  Between Westone patented STAR and Foam tips – you are covered to fit ear canal of any shape or form, but that still doesn’t guarantee that you will get the exact sound performance as it was intended by manufacturer.  You know how sometime you’re trying to find a perfect pair of shoes and can’t find that one specific half-size increment?  That’s exactly how I felt going from Medium to Large size eartips with W60, where the medium one gave me more open and detailed mids at the expense of a reduced bass impact, while the large one gave me a deeper and bigger low end response at the expense of thicker and more congested mids.  UM56 custom eartips were Godsend where I got a better fitment, isolation, and a more balanced sound signature.  But this combination requires an extra effort to align eartips with your ear canal and the shell.  The only way to perfect this fitment is by going with CIEM one piece design, exactly what ES60 has to offer.
Unboxing and Accessories.
Unboxing of ES60 put a smile on my face when I took the case from a shipping package.  For anybody familiar with Westone W-/UM-series IEMs, you're aware that packaging and accessories are nearly identical, regardless of the pricing or the driver config.  One accessory that always stands out for me is their bright orange vault box which kind of resembles a pelican case but still looks unique.  ES60 arrived in a “giant” orange vault case, a scaled up (probably 3x times) version of the original one which looked like “mini-me” in comparison.  While Pelican 1010 is the more common choice for a lot of other CIEM manufacturers, Westone decided to customize your experience starting with the case, which btw had a personalized tag with my name and a serial number, and I appreciate it was not printed on the case itself.
Under the cover of this “giant” vault you will find a custom partitioning for accessories, keeping everything neatly organized.  You're getting a cleaning tool, a bottle of oto-ease lubricant for your ears, a neat round cable management spool, a high quality cleaning cloth, and a silica gel pack (for humidity control) which goes right into the round holder for cable spool.  This was definitely a complete accessory package, though I would have liked to see a small carry pouch, maybe a drawstring type, for the occasions where you don't want to carry the whole case.  A small carry pouch or a zippered case is convenient to keep cables from untangling, especially if you decide to use aftermarket cables that won't fit around the included spool.
Unboxing & accessories.
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Removable cables.
As I mentioned in many of my other reviews, I always consider a removable cable to be an accessory.  Here by default you get Westone Epic cable, which is lightweight, thin, and has soft flexible wires with a tight rubbery jacket.  They are twisted on each side going to earpieces, and also inner-twisted (sharing a common ground) from y-splitter down to a nice rubbery right-angle headphone connector with gold-plated plug.   Y-splitter is compact, rubbery textured, and has a nice matching chin slider.
Going up to the earpiece plug, you will find a typical Westone short mmcx connector.  Any standard mmcx based connector will fit Westone IEMs, but Epic cable will not work with Shure, UE, or other headphones.  Westone stayed consistent with this connector type for their CIEM version.  I have read a number of comments with people having issues with mmcx connectors (across various headphone manufacturers, not just Westone).  Maybe I was just lucky, or perhaps I don't abuse my headphones as much, though I do test a lot of cables during my reviews, but I have never experienced any issues with mmcx based connectors.  Also, I would recommend to use Deoxit metal contact cleaner (gel or spray) for anybody who is experiencing intermittent connector problem.
Furthermore, just like with UM Pro series, this Epic cable has a flexible pre-shaped rubber memory wire that doesn't have any metal wires requiring constant re-shaping after you store the cable.  I absolutely love it and wish more manufacturers would use the same with their headphones.  You spend time adjusting the shape of a wire hook only to find it later ruined after you wrap and store it in the case; in here you don't have to worry about it.
Epic cable.
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Along with my review unit of ES60, I also received Westone latest Ultra-thin balanced cable: http://www.westone.com/store/index.php/westone-music-products/ultra-thin-balanced-cable.html.  It came in the Westone branded box, but as soon as I opened it up I quickly realized it was a re-branded Linum Balanced cable.  I have reviewed most of the Linum cables in the past and was always pleased with a quality of their 6-litz conductor wires (each made up of 7 individual strands) while still being super thin, ultra lightweight, very skin friendly, and nearly invisible when you wear it (matching a skin tone). 
The cable has a small rubbery straight gold plated 2.5mm TRRS connector, wired to work with Astell & Kern, as well as Cayin and Lotoo DAPs.  Y-splitter is a tiny separator of twisted common side cable going to the headphone plug and individual wires going to L/R headphone sides.  The chin slider has Blue/Red dots to IDs left/right side, and the headphone connectors have a nice rubbery plug with a good grip and a decent strain relief.  There is no memory wire because cable is so thin and flexible - it goes right behind your ears and stays secure.  MMCX connector is a shorter Westone type.
Considering this is a re-branded cable, one might ask what is a benefit of buying it from Westone vs Linum?  If you take into consideration the price (EU to USD conversion) and shipping cost, the difference is not that significant, and actually makes sense if you live in US or Canada to receive it faster and to have a local support.  Otherwise, better order it from Linum directly, especially if you want a universal mmcx connector.
Westone/Linum ultra-thin balanced cable.
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I know that some people don't believe in cables, and I'm not going to try to convince everybody to become a cable believer.  There are a lot of variables in the cable that affect a sound quality and contribute to its change, such as impedance of the wire, conductivity of the metal, purity of the material, and so on.  This sound change will be perceived differently by various people, and some will find it too subtle to even notice.  I'm sharing with you how I hear this change with my ears.  While a sound with Epic cable is smoother and warmer, Westone ultra-thin Litz cable brightens it up and enables balanced connection which helps a bit with soundstage expansion (like I hear it with AK120ii).
For my own personal preference, I wanted to improve retrieval of details in comparison to Epic and to improve low end impact in comparison to Balanced cable.  That's where I found Pure Copper cable to give me exactly what I was looking for.  Using Whiplash Audio TWcu v3 cable I was able to refine a sound signature of ES60 to my exact liking, adding more sub-bass and enhancing some mid-bass quantity.  Doesn't mean it will be everyone's cup of tea, but it was certainly the one for me.  Keep in mind, with CIEMs there is very little degree of sound customization because you can't do tip rolling, so cable swap is the way to go.
Whiplash TWcu v3 cable (w/L5 Pro).
Design and fitment.
I'm not going to pretend to be a seasoned CIEM user since I'm still discovering new grounds.  But from what I've gathered, acrylic is the most common and the easiest to deal with material when it comes to CIEM shaping.  Typically you find Custom monitors with a shell made entirely from acrylic material, and there are some made entirely from Silicone.  For example, UM56 eartips are 100% silicone made.  Westone decided to use the best of both worlds in their ES design, offering acrylic shell with a Flex Canal nozzle made out of silicone material with Dual Bore design splitting sound into highs and lows.  Multi-bore design is also common with a lot of CIEMs, allowing sound channeling to be partitioned and then combined/mixed outside of headphone shell when it enters your ear canal.  This is the most natural way to deliver a sound, and with a help of a custom CIEM shape - to have the best fitment and isolation.  Of course, you also have to take into consideration the passive crossover inside of the earpiece which takes care of filtering/partitioning the electric side of the signal coming from your audio source.
Technical side of the headphone design is very important, but you have no control over it.  This has been already taken care of by a professional team of Westone sound engineers.  But as a user you are in full control of customizing the exterior design by using Westone Labs ES Series Customizer on-line tool.  You get a chance to customize each earpiece separately since some people prefer a different color to quickly ID left/right sides.  As a matter of fact, that’s how I decided to proceed, with Blue earpiece for the Left side and Red earpiece for the Right side.  The level of customization is rather advanced with a lot of options, starting with a body color type and the actual color, faceplate type and the finish, and extra overlay plate or cover art.  A brushed steel overlay with W logo cutout was my choice, making the faceplate color/finish to shine right through it, while the body of the shell had corresponding translucent colors.  When you finish your Left or Right side masterpiece, you can move on to the other side or have an option to apply the same design to the opposite side.  Before you finalize the design, you also will get an option to select Epic cable with a different jacket color finish to match the artwork of earpieces or G2 cable with in-line remote and mic for either Apple or Android devices.
As you work through Customizer tool, every color and detail is reflected in the dynamic image of the earpiece that changes according to your selection picked from a drop-down menu boxes.  When I received the finished product, it looked exactly how I designed it, no discrepancies or surprises.  Looking closer, I couldn't find even a single flaw or imperfection, and I was especially pleased with a brushed steel overlay plate.  From outside it looks like the plate was right on top of the earpiece, but in reality it was under a smooth acrylic layer.  I looked close under the light with magnifying glass, and wasn't able to see or to feel the edge of the joint.  I mean, they had to put all the drivers, wiring, and crossover components inside and then seal it, but earpiece looked and felt like a solid nugget.
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The part of the design which surprised me the most was integration of silicone Flex Canal nozzle with the rest of acrylic body.  There is an absolutely seamless transition between these two materials - you can't even feel the joint.  I know it's hard to believe considering 2 different materials "melted" together, but it was connected forming one solid piece.  The whole idea of a silicone flex nozzle is to be able to improve the fitment when you insert these in your ear.  I don't have too many CIEMs in my collection, but have noticed that those with longer nozzle are usually harder to insert, while a shorter nozzle makes this process a lot easier (I'm still amazed how CustomArt CIEM fits in my ears).  With ES60 and longer Flex nozzle I actually had a little problem with my left earpiece (my left ear canal has a bit of an odd shape), but Westone took care of it and in 3-days with quick turn around I had it adjusted.  After shortening left earpiece (silicone part of the nozzle), I was back in business enjoying the improved fitment.
One thing to keep in mind, Flex Canal silicone material is not as smooth as acrylic and as a result of friction you ear canal needs to be lubricated before you place ES60 in your ear.  That's where oto-ease comes in very handy, or you can just give yourself a wet willy (works quite well too :wink:).  Another interesting discovery I found with ES60 and Flex Canal fitment, unlike acrylic shell which doesn't change its property - silicone material of Flex canal became a little softer, forming a better seal after a few minutes of use due to body temperature in my inner ear.  It's not exactly like Foam eartips that expand and seal better under higher temperature, not to the same extent, but still I felt that after a few minutes the seal became tighter while fitment still remained comfortable.  I was definitely pleased with it.
Sound analysis.
I know it's going to be hard for some people to believe this, but when it comes to a sound signature ES60 is a totally different beast from W60.  From what I gathered, ES60 doesn't have the same driver setup as W60, and they are tuned differently since you don't have to compensate as much with a custom as you do with a universal, taking into consideration canal resonance and insertion loss.  Majority of people are familiar with a warm lush thick W-series sound, and perhaps some would assume that ES60 will be no more or less the Custom fit version of the same sound signature, but it actually turned out to have a more reference quality sound.
Yes, I'm still talking about Westone and their 6-driver ES60 which I hear as having a balanced revealing sound signature with a reference smooth quality retrieval of details and slightly forward mids.  I also found a great soundstage expansion with above the average width/depth/height, no surprises here since a consumer oriented W-series always had a better stage expansion in comparison to performance oriented UM Pro series.  A sound was nicely layered with a feeling of airiness between layers, definitely a very good separation.  Don't get me wrong, a sound is still smooth, but definitely steps outside of your typical W40/W50/W60 warm and lush comfort zone - we are talking about a faster and a more detailed oriented balanced sound.
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Here is how ES60 compares to a few other headphones, inside and outside of Westone family.
ES60 vs W60 - ES sound is more transparent (W is thicker, more lush), soundstage expansion is the same, W has higher sub-bass quantity and stronger mid-bass punch, ES low end is more balanced, tighter, better controlled, more neutral in comparison, W lower mids are thicker, with more body and warmth, ES lower mids have a nice presence with a convincing body, but it is leaner and more detailed. Upper mids in W are smoother, more laid back, more organic, while ES upper mids are a little more forward, a little brighter, and more detailed.  W treble is smoother and doesn't have as much airiness, while ES is crispier, with a little more definition and better extension.
ES60 vs W60+UM56 - sound is getting closer now, similar transparency though ES is still a little better, same soundstage expansion, W+ has a little more sub-bass while mid-bass punch is similar, W+ lower mids are leaner now, but not exactly on ES level, but definitely leaner than W; upper mids of W+ have a little more clarity and the treble feels like it has more extension (in comparison to W), this performance is closer to ES, a little more airy than W but not as crisp as ES.  Overall W+ sound is less bloated than W and closer to ES, but still not at the same level.
ES60 vs Savant - S has a more neutral signature, soundstage has a little less width, S sub-bass is lower in quantity and mid-bass is a little slower and also not as strong, lower mids are little leaner, and upper mids are pushed back more in comparison to W, both have an excellent retrieval of details, just that S mids are a little smoother, and have the same level of transparency.  Treble has a similar extension, except ES60 has a little more airiness.
ES60 vs UM Pro 50 - UM has slightly more sub-bass and a stronger mid-bass punch.  ES has the same fast mid-bass but lower in quantity (more balanced).  UM lower mids are a little thicker, and upper mids in comparison pushed slightly back and a little bit smother.  Treble is a little bit smoother as well and with a little less airiness.  Overall UM sound could be placed between W and ES with addition of a bigger mid-bass impact.  Also, UM soundstage is narrower in comparison, but depth/height are similar. UM is a little smoother than ES, but not as lush as W.
ES60 vs DITA (modified w/TWag v2 gold cable) - Modified D has more sub-bass and bigger mid-bass impact, but the bass is not as tight or as well controlled, lower mids are a little bit thicker and upper mids are a little brighter, harsher, grainier.  Lower treble is brighter and harsher as well, getting closer to sibilance borderline level, while the level of airiness is the same.  Soundstage is very similar.  The impact of cable modification made D more v-shaped, while ES is more balanced and less fatigue.
ES60 vs Ei.xx - Ei has deeper sub-bass and a lot stronger mid-bass impact, bass is as tight and well controlled but scaled up in quantity, lower mids are very similar though Ei has it a touch thicker/warmer which adds more body to the sound, Ei upper mids pushed slightly back in comparison, smoother and not as detailed (less revealing).  Ei treble has a similar definition, but not as crisp and with less airiness.  ES is more balanced and brighter in comparison to a smoother Ei, which is warmer and smoother.
When I tell people that I'm using ES60 for critical listening, they raise their eyebrows because it's not what Westone is known for.  Westone house sound is smooth, lush, laid back, detailed (more detailed with flagship models), designed to sit back and enjoy the music during the extended listening session.  Don't get me wrong, ES60 still got all these trends, but I'm hearing a leaner and more detail oriented sound (not micro-detailed, but rather smooth-detailed) which is not as thick, more balanced, more dynamic, and better layered in comparison to everything else I have heard from Westone.  My CIEM/UIEM journey still continuous and I'm planning to review more multi-driver flagships from other manufacturers.  But based on everything I have reviewed so far, ES60 is definitely among the best I heard.  Due to various sound signatures, it's impossible to crown "one" UIEM/CIEM as the best.   Time and more listening to other UIEMs/CIEMs will tell, but for now I'm enjoying ES60 a lot, and really hope people won't discount them under an assumption of being just a custom version of W60.

As a bonus Review, I would like to talk a little bit about Westone TRU Hearing Protection Earplugs.  Despite being well known for their music products (headphones), since 1959 Westone has been specializing in custom earplugs and earpieces which is still a big part of their business.  Armed with a vast experience in hearing protection, today Westone developed a series of TRU hearing protection earplugs targeted at consumers and professionals requiring noise attenuation during concerts, nightclubs, sporting events, air travel, movies, etc.
The earplug itself comes in Universal and Custom fitments, where universal one is shaped in a form of a triple-flange eartip while custom is silicone made from in-ear impression taken by your local audiologist.  There are also professional and recreational tiers of these earplugs, depending on your application, in different price ranges.  But one thing they all have in common is the removable filter module which attenuates the sound across entire frequency range.  Unlike foam earplugs that block the sound, these filters are fine tuned to attenuate the sound without changing the quality of it.  These filters come in different flavors of 12dB, 16dB, 20dB, and 25dB attenuation value, and each one has a specific NRR (noise reduction rating) based on combination of the filter and the actual earplug type. 
Being quite familiar with UM56 custom eartips, I used to joke around about them being like two custom earplugs.  When I received TRU Custom earplug with WM20 filter, they were exactly like UM56 custom eartips but now with a removable filter.  Without a doubt, these are on a pricier side because of the custom nature, but considering other consumer oriented and universal options at a much cheaper price - you can find the right one depending on your budget and level of use.
My TRU custom fit hearing protection earplugs arrived in a nice professional packaging with a cool zippered pouch (will definitely use it for IEMs), 2 travel bottles of oto-ease lubricant (spray and gel), and a cleaning tool.  They were nearly identical to UM56 eartips and have the same piece of nylon string to assist in removing of earplugs after you wedge them into your ear canal.  Also, each earplug has blue/red ID to distinguish left (blue) and right (red) sides.
The direct link to the product is: http://www.westoneaudio.com/index.php/products/hearing-protection/tru-custom-hearing-protection.html but you can also find other TRU models under Hearing Protection part of the menu in Products pull down section.  They definitely fit great and do a fantastic job attenuating the outside noise - great at my work where our lab gets noisy and also at home where my kids get "noisy".
TRU active earplugs.
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TRU earplug fitment (did the best with this selfie and you still can barely see it).
Thanks for this great review! I see that you've also reviewed the UM Miracle: how would you say it compared to the ES60?
(I'm thinking of getting my first pair of CIEMs, and I'm deciding between the ES60, the UM Miracle, and the Hidition NT 6.)
@gollux1 : sorry, Miracle was a review loaner, don't have it anymore and it has been a very long time since i listened to it.  I only prefer to give a/b comparison of monitors I have on hand.
No problem. Thanks!