Westone MMCX Bluetooth Cable, 78548 - Reviews
Pros: wireless sound quality on par with wired performance, 8hr battery playback, aptX, MMCX Audio connectors, lightweight, symmetrically-balanced design.
Cons: mmcx only connector, elevated noise floor (noticeable with IEMs prone to hissing when "wired"), no storage pouch.

The product was provided to me free of charge for the review purpose in exchange for my honest opinion.  The review was originally posted on my blog, and now I would like to share it with all my readers on head-fi.
Manufacturer website: Westone, also available on Amazon.
*click on images to expand.

Even so Bluetooth wireless protocol has been around for many years, it constantly evolves and makes its way into new applications.  In early days we were perfectly fine with a bandwidth-limited, compressed, and down-sampled audio transmitted to a single headset for a wireless use with a phone because it felt liberating talking on a flip-phone without holding it next to our ear.  Today this wireless technology is integrated into smartwatches and fitness trackers, fancy keyboards and game controllers, high res audio headphones and much more.
Evolution of the wireless audio probably had the most noticeable progress thanks to updates of various BT protocols and codecs.  When the first wave of wireless stereo earphones arrived, people were just happy to cut the wires.  At that point, sound quality was not at the top of the priority list until aptX codec was introduced, and the next wave of earphones stepped it up with more clarity, expanded dynamics, and improved bass extension, though the bottleneck was still around cheap drivers.  Another solution involved using a wireless dongle, but it required plugging in your existing attached cable which kind of defeats the purpose of true wireless.
The latest trend in wireless earphone technology is upon us, and I'm surprised it took that long to get here.  Considering the implementation of removable cables in higher end IEMs/CIEMs and the popularity of sports wireless earphones with interconnected earpieces, both were combined to have a short cable with in-line remote and mmcx connector termination to attach compatible IEMs/CIEMs.  Though I'm also noticing similar announcements from other manufacturers about their upcoming budget releases, Westone was one of the first out of the gate with their new advanced design which I’m planning to talk about in this review after spending the last month with their BT Cable.
Unboxing and accessories.
Arrived in a compact packaging box, it has a nice cover art which can give you an illusion of the front and the back of the same in-line remote with a cable cinch underneath it.  The full picture is not revealed yet, keeping you in suspense until you flip the box on a side.  Also on the front cover, I like the pride of mentioning "Designed in Colorado, USA" underneath of Westone brand name – a nice touch.  On the back you get some extra info and the description of what's inside of the box, while on one side of the box you will find a detailed list with all the key features and the other side has a full picture of the cable.  That's when you quickly realize there are two "remote" looking pieces on each side, symmetrically balancing the design of the cable.
With a box cover off, you will find a foam insert with a cable securely wrapped around it and a quality charging usb to micro-usb cable.  Also included was a detailed Quick Start guide which I actually found to be very useful, especially the pages describing Buttons and LED functionality.  Definitely don't loose this guide, it comes in handy.
Overall, it was a basic packaging with minimum accessories, nothing too fancy, but I would have loved to see some kind of a storage pouch.  I'm sure many will use this BT cable interchangeably with a regular cable, thus a storage solution when not in use would be a good idea.  Also, I wish Westone would have mentioned explicitly in print about this being a universal MMCX connector.  Their stock Epic cables use slightly shortened mmcx connectors making that cable incompatible with other universal mmcx connector IEMs.  Some could misinterpret "Westone MMCX Audio Connector" as made specifically for Westone only monitors, while in reality BT Cable has a universal MMCX connector which I have tested and found to be compatible with all other regular mmcx IEMs/CIEMs.
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Prior to receiving the final production sample of BT Cable, I had the opportunity to test their early prototype.  I thought it was quite original to split the in-line remote into two symmetrical pieces on each side of the cable.  The piece on the right has in-line remote with Vol +/- (also doubles as track skip), Power/Play/Pause/Call multi-function button, and micro usb charging port and mic pinhole.   The piece on the left contains a battery.  After collecting the feedback from prototype testing, Westone went back to the drawing board to optimize the design by reducing the size of these L/R pieces, cutting the weight down to 12g, and improving the battery performance to reach 8hr playback (confirmed in my testing).
The housing of these in-line pieces is made out of high impact plastic with an aluminum matte plate over the top.  The cable attachment on both ends of the housing has a nice strain relief and the housing itself is slick and compact.  As I mentioned before, left piece only hosts a battery and has Westone name printed across the surface.  The right piece has in-line remote with 3 control buttons.  All buttons have a tactile response with a nice feedback.  The multi-function Power/Play/Pause/Call button is in the middle and has a raised round shape which is easy to id without looking, just by sliding a finger, and Volume buttons on each side are flat with a raised +/- which is easy to id by touch as well.
Even though there is a narrow separation slit between the buttons, they do look like being well sealed since BT Cable is certified to IPX4 sweat/water/dust resistance rating.  I didn’t dip the cable into the water, but have worn it on a few “sweaty” occasions while exercising or doing backyard work, and never experienced any issues.  The same with micro-usb connector where the rubber flap tightly seals the port opening to protect it from moisture, and I'm sure mic pinhole probably has some internal cover screen to meet IPX4 rating.
The cable going to MMCX connectors and on the back around your neck is all covered in a soft rubbery shielding material which feels very durable.  The part of the cable going to MMCX connector housing has a round shape for a more comfortable fit especially when worn over the ears.  The connector housing is rubbery with a nice strain relief and a secure grip.  It uses new Westone MMCX Audio type of connectors designed with a tighter tolerance and higher quality material.  This rubbery connector housing has a slightly extended lip for a tighter seal of the gap when you attach the earpieces.  Connector joint was tight, snappy, and secure with most mmcx IEMs/CIEMs I tested it with.
The cable on the back is narrow and flat for a more comfortable fit as it goes behind and around your neck.  Plus, it has a cable cinch with a nice sliding friction which never feels loose.  Obviously, the design needs to be universal to accommodate every shape and size, thus cinch adjustment is important.  Many other sports earphones with a wire behind your neck have a plastic clip you have to thread the cable through, bending the wire to extreme which can causes a memory effect and possible damage.  And those clips are not easy to adjust on the go.  This particular cinch design feels secure and very easy to adjust without a need to take the cable off.
Location of LED indicator was the only thing about the design which I wasn’t too crazy about.  LED indicator is very important because it shows power status, pair up status, low battery notice, and charging status.  The LED is located between the Power and Vol- buttons, shining through a slit opening.  It’s bright and multi-colored (blue and red), but in order to see it you have to be sure to press the Power button with your thumb resting across Vol+ button so you don’t cover Vol-.  It’s not a showstopper, but rather something you need to get used to, otherwise you will cover the LED light with your thumb if it rests across all 3 remote buttons.
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BT pair-up and Controls.
Bluetooth pair up was effortless, just a common step of scanning for available devices, selecting “Westone BT” from the list, and being instantaneously connected to Call and Media Audio on my Note 4 or Media only on my X7 Android DAP.  BT Cable design utilizes the advanced CSR8645 chipset, providing compatibility with the latest BT4.1 and support of popular codecs such as aptX (for Android devices) and AAC (for iOS).  Along with that you will also have a support of all the latest Wireless profiles, such as HFP1.6 (hands-free for making calls), A2DP1.2 (advanced audio distribution for audio content), and AVRCP1.4 (audio/video remote for playback and volume control).  CSR8645 even has a hardware support for a headphone stereo separation to make soundstage more natural.
Regarding controls, I already touch base about 3 multiple function buttons and one multi-function LED indicator.  In more details, Vol+/- doubles as volume inc/dec with a short single press and track skip with a longer (1s) press.  Also, pressing both Vol+ and Vol- clears paired up devices (supports 2 devices at a time).  The middle Power button turns the power on/off with a long press and corresponding LED indicator flashes (blue+red once).  Typical long press (5s) enters the Pair Up mode, and during playback you use a single press Play/Pause for the audio or to receive/end incoming call.  Double click brings up a voice search using either Google or Apple’s SIRI.  With LED, you see blue when you are paired up or the charge is complete and red when charging or flashing red when battery is low.
In general, buttons are easy to press without looking, the logic of controls is common across many other BT headphones, BT distance coverage was good up to 35ft in open space where I didn’t notice any dropouts, and call quality was clear despite mic pointing back.  The only comment here is a loud beep when you change the volume.  It’s not a showstopper, just a bit annoying especially with a piercing high beep indicating that you reached the max volume level.
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Source pair-up and Sound quality.
Here are some observations I made while testing BT Cable with different wireless sources and comparing wired vs wireless performance.  For this test I decided to use Pinnacle P1 IEM because it needs to be pushed a little harder to drive the volume to a decent level.
Using FiiO X7 Android DAP which doesn’t support aptX, I found in wired mode to have a normal listening volume level with plenty of headroom, but in a wireless mode I had to raise X7 volume to the max and adjust BT Cable volume a few clicks below its max.  Also, seems that actual X7 volume change from 50% to 100% didn't have too much effect on BT Cable volume.
With my Galaxy Note 4, which supports aptX codec, I hear a significant sound improvement when comparing wireless vs wired on my phone, where in wireless mode BT Cable sound was more resolving, bass had more control and was tighter, upper mid had more details, and treble had more sparkle.
Being curious about added bonus of aptX codec, I compared Note 4 (w/aptX) vs X7 (w/o aptX) and found the difference to be rather subtle, maybe treble being a little more crisp with aptX while w/o aptX it was a little smoother.  Also, with Note 4 I had more volume headroom using my phone with BT Cable, even being able to push volume a little bit louder.  Don’t have explanation for that, just stating how I hear it.
I also tried AK120ii, and found that I had to push volume of the DAP to the max, and adjust BT Cable volume a few ticks down, but I was able to drive P1 louder in comparison to X7.  The difference between Note 4 and AK120ii was similar to what I found with X7 - very subtle, just improvement in treble sparkle.
Pair up Test.
The following pair up test was done using X7 Android DAP to compare wired vs wireless performance.  Also, another reason for using FiiO DAP is that X7 doesn’t support aptX, thus iOS device users will get a better idea about the Cable performance.  Furthermore, with hissing level being one of the important test criteria, my scale from the lowest to the highest refers to: very faint < faint < noticeable < very noticeable.  Keep in mind that hissing will vary based on the spec of earphones (sensitivity, impedance) and your source's amp.  Depending on the source, the same pair of IEMs could be dead silent with one DAP and hissing with another one.  If you find your pair of IEMs/CIEMs to hiss with a cable, most likely it will hiss with BT Cable and that level could get a little higher in wireless.
Westone W60
W60 - very faint hissing; nearly identical sound quality from sub-bass to treble extension, soundstage is almost as wide as wired.  Volume on X7 needs to be pushed higher.  Excellent snappy fit of the connectors.
Fidue A83
A83 – very faint hissing; had to push X7 vol to the max and BT cable vol 2 clicks below the max, very similar sound, except wired soundstage is a little wider and I hear a touch more sparkle in upper mids/treble, a little more airiness.  Connector fit was very tight and secure, but not as snappy, perhaps due to Fidue’s customizable connectors.
Westone UM Pro50
UM Pro 50 - very faint hissing; nearly identical sound quality, maybe just a touch warmer with BT cable, but overall nearly the same.  Also the soundstage width was nearly the same.  Good volume control range.  Connection was secure and snappy.
Westone AM Pro30
AM Pro 30 - noticeable hissing; nearly identical sound quality, maybe just a touch warmer with BT cable, but overall almost the same.  Also, the soundstage width was nearly the same.  Good volume control range.  Connection was secure and snappy.
HUM Pristine-R
Pristine-R - noticeable hissing; sound quality is nearly identical from sub-bass to upper treble extension, soundstage reaches almost wired performance.  Good volume control range.  Connection was secure and snappy.
Oriveti Primacy
Primacy - very faint hissing; very similar sound from low end (both extension and impact) to high frequency sparkle and airiness.  The difference is in a little narrower soundstage when wireless.  Connection was secure and snappy.
MeeAudio Pinnacle P1
P1 – very faint hissing; sound is nearly identical, though wired was a little wider and had more headroom in volume adjustment.  Connection was secure and snappy.
Campfire Audio Andromeda
Andromeda - very noticeable hissing; nearly identical sound quality, reaching out deep sub-bass and high treble, soundstage was wide enough too, almost reaching the wired performance.  It seems that Andromeda is more sensitive to X7 volume change.  Connection was secure and snappy.
Fidue A91 Sirius
A91/Sirius - very faint hissing; nearly identical sound quality (from deep sub-bass to sparkly treble), soundstage width reaching almost wired performance.  Good volume control range between DAP and BT cable.  Connection was very tight, secure and snappy.
Westone ES60
ES60 - noticeable hissing, sound quality is nearly identical from sub-bass to treble; soundstage width is not only the same, but actually a little wider in wireless (!!!).  Good volume control range.  Connection was secure and snappy.
Ultimate Ears UE900s
UE900s - faint hissing; very similar sound quality, the same low end extension and treble sparkle, wired connection has slightly wider soundstage and a little better dynamics, in contrast wireless connection had a slightly congested sound.  Connection was secure and snappy.
In my recent review of Westone latest AM Pro 30, I jokingly asked: "who said you can't teach old dog new tricks?", while with BT Cable I might as well state: "who said old dog can't teach you new tricks"
 This new product from Westone really caught me by surprise, and I didn't expect them to venture outside of their comfort zone of traditional wired IEMs/CIEMs.  But in order to stay relevant and to continue generating the buzz you need to take a risk, and I think it paid off in this case.  Actually, the bigger risk here is that sooner or later similar products will emerge from other manufacturers, and I'm already starting to see other releases, though their battery is nowhere near the playback time of 8hrs and not all of them use the latest CRS chipset supporting atpX and other updated BT profiles.
Westone BT Cable doesn't just look impressive on the paper, but it has a durable build and a unique symmetrical design keeping battery away from the rest of the control circuit.  Its wireless performance is on par with wired using majority of IEMs/CIEMs I have access to.  There is some hissing, but mostly with in-ear monitors that already exhibit it when wired - BT Cable just amplifies it a little more.  Even so new Westone monitors only support mmcx connectors, thus a reason for this only option on BT Cable, I hope that in a future 2pin variant will be available as well, or maybe they will come up with a modular design to interchange the cables.
Yeah $150 is pushing it. Would probably consider it if it had those low profile memory hooks their Pro/Custom series cables have. This cable doesn't look like it's gonna last (I've gone through 2 of their W-series braided cables in a year).
Another item of note is how this will handle your phone calls.  On my iPhone 6 Plus, When I answer a call, this cable provides a sensitive loopback audio.  This means that, even though you have two ears plugged, you can hear yourself clearly when you talk.  Anyone with experience taking a call with two ears plugged with iems knows how annoying it can be.  This is a very nice feature and reminded me of the UE9000, which was the first I remember as having it.  I actually wish there was a way to turn it on and off at times other than phone calls.
As for the microphone quality to the person on the other end, its mediocre, unfortunately.  The person you're calling will clearly hear the environment around you, so don't expect to be able to do calls in cafe bars, etc.  If microphone DSP noise-cancelling is very important to you, you still can't do any better than the Plantronics Focus.  Its decent sound quality, but won't match a good TOTL on this Westone Bluetooth cable.  I have the Plantronics Focus, and I have trouble deciding which is more important, good call quality, or good sound quality during workdays.  After work, the much easier choice is to use the Westone, which I use on my FX850's.
Great review twister6! thanks for going through that list of IEMS/CIEMS and giving us a taste of what it sounds. was contemplating on getting Tennmak Bluetooth cable which is on sale for $17 on aliexpress.com but may hold off for westone.