Unique Melody MEST Mk II – the bone conductor’s revenge

Acknowledgement

I purchased the MEST Mk 2 from Andrew at MusicTeck USA at full retail price (RRP was $1499 at time of purchase), with the intention of reviewing them. No input has been sought or received from MusicTeck or Unique Melody with regards to the content of this review – the opinions expressed below (however ill informed) are 100% my own.

This isn’t the first MEST model I have owned, so to read my previous review of the original MEST, please click here , and to read the companion review comparing the Mk 1 and Mk 2 models please click here . Some elements of the comparison review are reused here for consistency, so if you have already read that then feel free to skip to the interesting bits!

Background on the MEST series

In the modern audio landscape, it often seems that progress waits for no man (or woman), with new models and technological innovations hitting the shelves almost weekly. This certainly holds true for the Chinese IEM giant Unique Melody – my last published review on this site was an assessment of the MEST Mk 1 (see link above), and less than 12 days after my first review was posted, I was already working on a comparison write up covering the upgraded Mk 2 model. Since I started writing this (now third) piece of UM prose, the company have announced the release of a new bone conduction flagship called the Mason FS. Whatever they put in the water in that part of China, it certainly seems to do wonders for the work ethic.

Reading around the story behind the new version, it would appear that the UM guys and girls have been reading every single review of the original model, making a series of small but important tweaks to the design, accessories and sound to address pretty much all of the non-positive comments made in the slew of reviews this IEM has received since launch (of which there really weren’t that many to begin with). The tuning has been “adjusted” for a more Western target market, with slicker ergonomics in the shell and cable designs and a much more premium experience with accessories and general cosmetic appeal. The driver design remains largely the same, with improved airflow around the 10mm dynamic driver being used for the low end and a new “B2” bone conduction driver, which now operates across a much wider frequency range than the original – UM call it a “full range” driver, but like most of the commercially available bone conduction headsets out in the wild, bass is not a strong point of this particular driver type so I’d categorise this as more of a “lower mids to treble” driver personally.

Driver design

Tech Specs

Initial impressions on sound

In general terms, the Mk2 offers a “W” shaped tonality. If you aren’t familiar with the various audiophile letters that get used to define the sound of headphones or earphones, this basically means that the bass, mids and treble are all roughly in line with each other, with no particular section deviating too far from the others in terms of overall presence or quantity. So, why not just call them “neutral”? The W in the shape indicates that these aren’t just ruler flat, and there is some careful sculpting of the signature as you rise up from bottom to top to emphasise (or de-emphasise) certain aspects. So, these are balanced, but definitely not pure reference, with some very careful curation of the overall tuning to present a sound that is musically engaging, rather than dry or sterile.

With regards to the bass, this is a little north of neutral in quantity, but I wouldn’t call it a bass head level of volume. There is plenty of oomph in the drivers where needed, with a decent balance between sub-bass and mid-bass to provide a nice sense of physicality to proceedings, as well as a little slam. Texture and detail is top notch, with the MEST Mk2 driver being able to produce tight, detailed bass with plenty of body but without a lot of flab or reverb. It kicks when it needs to, but keeps a tight grip on proceedings while doing so, coming across as somewhere between textured and ever so slightly dry to my ears.

The bass tapers down into the midrange, picking back up again as it pushes both male and female vocals forward on the stage. This is middle “spike” of the W shape, and helps the MEST provide a sense of scale. The midrange is mildly warm, with enough substance to provide a nice sense of thickness to both vocals and stringed instruments. Detail levels are very high, with plenty of separation around the various elements of a track that allows the MEST to avoid sounding congested or stuffy. The mids are tuned more towards the emotive end of the spectrum rather than classically neutral or flat, borrowing a little from the old Final Audio “rawness” in the presentation that captures the emotional weight of a singer’s voice.

Treble is again similar in quantity (possibly slightly more forward in both volume and stage position), with the now-classic Sonion EST style of presentation which is smooth and weighty but still highly resolving. This is backed by both the BA and BC drivers as well, and can be considered a highlight of the Mk 2. It isn’t the most open or sparkly presentation you will ever hear, but detail levels are again at flagship-tier, and the sheer effortlessness of the presentation helps the MEST cut through the hottest of tracks without so much as a flinch.

Staging is on the grand side, with a truly three dimensional sense of space that sometimes seems to wrap around behind the head of the listener, expanding outwards in all directions and allowing plenty of space for each instrument or vocal to inhabit their own distinct audio space. It isn’t the widest or deepest IEM I’ve ever heard, but I haven’t heard anything yet that can compete in all three directions.

Separation and layering are also flagship-worthy, with the MEST Mk2 being able to keep each different strand of music neat and distinct, and placing everything with pinpoint accuracy in the expanded 3D soundscape. This really is a treat if you are into IEMs that present a clear sonic image, and the addition of a small sense of added “reality” to the sound that accompanies the use of the bone conduction drivers is definitely helpful here.

Ergonomics and build quality

Starting with the design, the Mk2 sport a classic pseudo-custom form factor, with a noticeable but not too aggressive contouring on the inner face of the IEM, and a slight “lip” at the top of the inner shell to lock into the concha. It isn’t anywhere near as agressive as some of the pseudo-custom designs out there on the market now like the Ibasso IT03 or the Stagediver series, but the smooth lines definitely help it fit slightly better than a standard “flat faced” in-ear.

The IEM is probably medium-sized in terms of height and width, and above average where it comes to depth, packing a lot more girth there. As a result it probably won’t sit flush in the ears unless you happen to be packing an ear canal the same size as the Grand Canyon, so if you are a side sleeper and looking for the Mk2 as your latest pair of sleep companions, you may want to rethink. They aren’t at old-school JH Audio levels of protrusion, but this is definitely a monitor that doesn’t disappear when worn. The contouring dos help a lot with the fit, allowing an easy “deep fit” of the IEMs for me. This is crucial in getting as much of the IEM shell into contact with the surface of the ear, so that the bone conduction voodoo can take place.

Cosmetically, the Mk2 is definitely a looker. UM have moved to a full carbon fibre shell rather than just the faceplates on the original, and the addition of small flecks of gold into the interwoven black carbon fibre design is a classy touch. The finish on the shells is of a very high quality, feeling smooth and solid in the hand, without any obvious imperfections or joins. The face of the IEM follows the design of the shell, with metal “UM” and “MEST” logos on the left and right shells. The only other thing that adorns the front face of the Mk2 (apart from those gold flecks and carbon fibre) is a metal venting port for the dynamic driver. It is slightly raised from the rest of the faceplate, and adds a nice eye-catching detail to the otherwise smooth and fairly understated design of the IEM.

Overall, the design is both functional and good-looking, with a high class feel of fit and finish.

Accessories and unboxing

From the look and feel of the box to the included accessories, the Mk2 definitely gives the sort of experience you associate with a high-end piece of audio gear. It isn’t overly ostentatious or ridiculously crammed with branded accessories and a million pieces of hardware, but it definitely feels well thought out and suitably expensive.

Starting with the box, the MEST Mk2 comes in a fairly small squarish “jewellery box” type affair, reminiscent of some of the Austell & Kern collaboration pieces with its removable drawers and black lining. Opening the box, the first thing you see is a rectangular blue and black carry case from Korean manufacturer Dignis. It isn’t designed to provide the ultimate in crush protection, but it is semi-rigid and very nicely designed, with removable separators on the inside to keep the IEM shells from touching and the cable neatly aligned. It is more or a transportable than a portable case, as it’s a little large to fit in the front pocket of a pair of jeans, so feels more likely to get thrown in a bag or jacket pocket if you intend to take the MEST on any trips.

Deliving further into the package, the included load-out of tips and cable is a nice touch. The Mk2 comes with Comply foam tips, some own-brand UM silicone tips in various sizes and a three-pack of Xelastec tips, made from sort of sticky translucent rubber. This is significant as apart from costing the best part of $30 for a pack (yes, $30), they are the after-market tips that were most commonly suggested on various internet forums for pairing with the original MEST. It definitely feels like someone at UM has been paying close attention to the internet suggestions from happy end-users here, and their inclusion definitely takes the usability of the package up a notch straight out of the box, and saves you having to try and track down a set from one of the Asian retailers that sell them.

The included cable is an aftermarket affair called the UM Copper Mk2, which is a sleek black rubberised affair from the well-known HK cable manufacturer PW Audio. The cable is a bespoke design for Unique Melody, with a branded metal y-split in anodised black and beautiful and study looking connectors at both ends, again branded with the UM logo. The whole feel and for of the cable is pretty premium, and its low-profile black on black aesthetic plays very nicely against the black and gold shell design. UM seem to be moving away from their more traditional extruded 2-pin sockets, so the cable (and IEM) not sport a standard flush 2-pin CIEM connection, so the cable can be used with other 2-pin IEMs or swapped out if needed. I tend to prefer a recessed 2-pin socket as I feel it offers a little more protection against bending the pins, but that’s more of a personal preference than a particular shortcoming.

The remainder of the accessories consist of a credit-card sized warranty card, a magnetic shirt clip and some associated bits and pieces. Overall, I think UM have done a pretty good job of packing in some high quality gear alongside the IEMs, giving a good impression of quality throughout, and certainly befitting the price tier the MEST finds itself in.

Bass

Please note that these impressions are based on my Mk2 pair with over 100 hours of actual listening and a similar amount of burn-in on the clock at time of writing. I’m neither pro or anti when it comes to burn in, but have removed it as a factor here just for simplicity. For the record, I think the bass quantity may have increased slightly, but I have not noticed any other audible changes. All impressions given here are made using the Ibasso DX300 in medium gain or the Cayin N8 in medium gain and high current mode, using the 4.4mm stock cable that came with the IEM and the Xelastec medium tips

The Mk2 produces a nice, full sounding bass – the emphasis is weighted to the lower end of the scale, and provides a sound that is full but not overbearing or bass head in nature. The refined dynamic driver design pushes out a lot of texture, with plenty of detail and control. It hits low and slightly dry, but is pretty decent in terms of quantity, pumping out plenty of volume where the track calls for it. Starting off with “Palladio” by Escala, the opening cello sounds raw and gravelly, with a real etching of texture, carrying plenty of weight. The relative dryness keeps everything very firmly under control, allowing the subtle click in the lower left corner of the stage to come through clearly at the 20 second mark, despite the larger than neutral volume of output. There is no masking or bleed apparent into the higher frequencies, keeping everything feeling taut and very precisely controlled.

Similarly on “Hello, It’s Me” by Sister Hazel, the MEST sounds full and textured, packing in plenty of powdery resolution to the bass notes. It does forego a bit of the velvety richness that the bass guitar usually imparts as a trade off, so this isn’t the slinkiest or most chocolately delivery you will ever hear, but the added sense of detail definitely makes up for it.

Sub bass extension is pretty impressive, the Mk2 easily dropping down to the low reaches of tracks like “Disc Wars” by Daft Punk without breaking a sweat, and making the temples vibrate nicely to the opening bars of “Heaven” by Emile Sande. Quantity and general tuning leans towards the same sub-weighted style of bass tuning that is becoming increasingly popular in the mid and top tier IEM market. The overriding impression is of an IEM that can push plenty of air, but which keeps a Kung-fu grip on all the instrumentation when it does so.

“Bad Rain” by Slash rounds off the quick bass test, and tells a similar tale, with the Mk2 papering a layer of fine textural detailing on to the outside of each bass note. It’s subtle, but again that word substance springs to mind. The Mk2 bass carries a decent solidity and sense of heft, but also manages to supplement it with exemplary control, which is pretty impressive for a dynamic driver.

Mids

The MEST carries that low end weight through to the midrange, presenting vocals and instrumentation with a little more roundness and heft than strictly neutral, but without losing any of the clarity. The whole frequency range is pushed forwards in the stage, forming the middle uptick of the predominantly “W-shaped” tuning.

Something like “Song For Adam” from Gregg Allman’s final album sound a little chestier than absolutely flat IEMs present it, capturing the phlegm-inflected intonations of the track with a sense of substance. Similarly, “Might As Well Smile” by Beth Hart rolls along with a substantial sense of warmth and body, giving Hart’s unusual voice both rasp and roundness, playing well against the delicate finger-picking of the guitar at the 2:30 mark without losing either thread. In all honesty, the Mk2 probably adds just a touch too much rawness to Hart’s vocal, pushing it forward almost to the edge of sharpness or sibilance. It manages to steer clear of sounding unpleasant, but if a lot of your music collection has vocalists who sing in the same sort of ranges, you may not be quite so lucky. Firing up one of my harshness testers, “Whiskey And You” by Chris Stapleton surprisingly sails through, the country troubadour’s voice sounding full of p!ss, vinegar and gravel as always, but not sandpapering the eardrums at the troublesome bridge section (1:48 on the track). in fact, the extra weight the MEST brings this IEM around helps to add some fat to the gristle of the vocal, giving just enough smoothness to the raw edges to let them slide on without too much trouble.

This is actually somewhere where preference will play a part – for those who found the original MEST to have a slightly thin or less voluminous delivery around the middle, the extra meat on the bones will be the final piece in the jigsaw. For those who love a (comparatively) leaner, airier sound in the mids, the Mk 1 might well provide that a little better. The slight bump in note weight robs the stage of a little air and separation on the revised version – the Mk2 is still top tier when it comes to separation, but it doesn’t quite give the same sense of distance between each note that the leaner Mk1 tuning managed, trading it for a bigger note size and a better feel of “weight’.

Listening to “The Cold Wind” by Greta Van Fleet, the 70s guitar tone feels weighty and emotional, still managing to keep the instruments easily identifiable and positioned in their own zone on the stage, but not quite to the extremes that some technical IEMs can offer. There is plenty of definition on offer inside the notes, the MEST doing an admirable job of presenting the jangling guitar chords with an analogue tone but still with clear delineation between each string being played. It isn’t ultra-warm or “wall of noise” style, but if you prefer your music served up slightly warm through a decent tube amplifier, you’ll be on the right sort of wavelength for what the MEST wants to present.

Trying some crunchier rock, “World On Fire” by Slash and Myles Kennedy kicks off with its expected vigour, the choppy guitar resolving nicely in either ear with plenty of weight to the staccato riff that runs through the track. The note edges aren’t as sharp and cutting as they can be on some IEMs, but the detail is still all there, so the trade off is definitely worth it. The MEST handles the frenetic pace of the track without smudging or blurring, the multi-driver setup keeping pace easily with the music and maintaining the technicality without losing the analogue “vibe”. Trying out “Shadow Life” from the same album, the riffing there is even more stop-start, and the MEST again has no issue with the pace. It stops and starts on the proverbial dime, giving the guitar a genuine weight and substance in the ear without making it particularly thick or gooey. Overall, for modern rock music, this is an IEM and a tuning that will be very difficult to fault.

Firing up some Shawn Mullins for my final comparison track, “And On A Rainy Night” from his recent Revival version of the Soul’s Core album is up for scrutiny. Mullins’ vocal on this track is part-drawl, part subterranean hum, and the MEST packs it full of texture. Mullins’ raspy tones are beefy and well fleshed out on the MK2, and absolutely dripping with texture. This track goes for the thicker sort of emotional resonance that the Solaris 2020 is a master of from Campfire Audio, pushing out a sound that is warm and inviting but that doesn’t hide the rough edges of voice or instrument, just puts a little polish on them until they are smooth enough to listen to without discomfort.

Overall, the Mk2 midrange is a pretty Goldilocks affair – not too thick, not too warm, just right. It carries detail in spades without feeling dry or lean, and is as technically impressive as any IEM I’ve heard in the sub $2.5k bracket while still retaining its emotional punch and character. It is probably the biggest area of “improvement” (for my tastes) from the original model, and should have enough of everything to please most listeners.

Treble

The treble is the area where I am able to discern the least difference between the old and new variants. If you haven’t heard the Mk1, this translates to a presentation that is a very classic EST style reproduction, clean and solid with the treble sounding pretty effortless as it churns out gobs of detail.

Treble isn’t hugely forward on the stage, carrying a nice bite but not pushing too far into the listener’s eardrums. It can’t be described as laid back, but neither is it screaming hot or hugely elevated. The EST and bone conduction combo give a very palpable sense of air to the upper areas of the mix, allowing a lot of black space around the notes to give the impression that they are hanging in a fairly open auditorium sized space, rather than being boxed in to the usual confines of a studio recording room.

Starting on my test tracks, “Oceonic” and “Kismet” from the classical fusion quartet Bond are up first. Both tracks are heavy on the violin and synth, and the MEST paints a nicely open picture of the fluttering synth notes that weave around the main violin refrains. Violin is solid but delicate, not pushing too far forward in the ear but maintaining a neutral position and sense of delicacy. Similar for the synth effects, these swirl and sparkle throughout the tracks without drowning the instruments underneath.

Both plucked violin harmonics and the bowed solo elements feel nicely emotive, the dual EST and bone conduction pairing avoiding the brittleness that an all-BA setup can give either of these tracks. In a lot of ways this is “classic” EST tuning, solid yet refined and never sounding like it is harsh or strained. In many ways, the treble is served up as a complementary dish to the mains of mids and treble, rather than setting itself up as the main course, so if you need a heavily treble emphasised or aggressive sort of sound, the MEST probably wouldn’t be your first port of call.

Trying some more traditional dance tracks, another double header is up next: “We Found Love” and “Drinking From The Bottle” by Calvin Harris’ third album 18 Months. This album is mastered quite hot, and the MEST is pretty faithful to the underlying recording, with both tracks coming across as a little on the thin and sharp side. It isn’t unpleasant by any means, but there is definitely a whiff more vinegar to the electronic instruments in the top end, which sits in high contrast to the more organic and rounded tonality of the mids and bass underneath. The detail levels here are high, with the micro-echo of the opening refrain clicking away in the left and right ears as the track winds into high gear. Rihanna’s voice is strong but again, a little more on the thin and aggressive side than it sounds on some of my other gear.

Looking to see what my usual harshness testers sound like, “Starlight” by Slash is up first. The harmonic heavy intro plays out wonderfully organically, with the dissonant ping at the 8 second mark sounding emphasised but not jarring. There is a richness to the harmonic overtones that fleshes out the jagged edges, again evoking the way a good tube amp usually colours the music. Myles Kennedy’s voice is smooth and buttery even as is scales upwards towards falsetto, hitting the helium highs without getting harsh in the ear. “Whiskey And You” by Chris Stapleton is my last tester for harshness or sibilance, and again the MEST rolls though unscathed. Stapleton’s voice has plenty of grit and gruffness with the MEST presentation, it just steers away from the unpleasant sharpness that the track can have on some of my gear. (As an aside, if you ever want to hear a track by a brilliant musician that appears to have been recorded and mastered in a cement mixer full of food blenders on a one way trip to the centre of the sun, this track is a good place to start.)

My penultimate treble tester is “Coming Home” by the prog supergroup Sons of Apollo, specifically to check the cymbal reproduction. This track is driven by a propulsive drum barrage from Mike Portnoy, and the cymbals here give a splashy ceiling to the grungy rock going on underneath. On the MEST, the speed and detail is all there, but the cymbals fall in line with the rest of the treble, taking more of a back seat to the music underneath rather than providing a real counterpoint. Decay feels on the more organic side, possibly coming through as a little muted, each crash lasting about a second before fading quickly into the black background. In terms of speed, the MEST keeps up very well with the complexities of the track, the high speed hi-hat motif that kicks in around 2:52 sounding crisp and ultra-defined as each note is picked off. This isn’t a monitor that will struggle with any sort of blurring or lack of definition, despite the more laid back nature of the high end – there is plenty of speed on tap to keep everything moving.

The last cymbal test track is “The Chain” by Black Stone Cherry. This again paints the cymbals a little more muted than my ideal preference, but keep pace with the hi-hat trickery and general drum kit thrashing that cuts through the chunky riffing going on. Again, it’s more a case of speed than emphasis, but the more natural and organic “tsss” style of cymbal decay rather than the ultra crystalline “tsssssssss” you get on some treble boosted or more “sparkly” sets sits well with the overall tone that Unique Melody have gone for here.

In summary, the treble is technically excellent, with a smooth and solid tone that sits roughly in line with the other two frequency ranges in terms of overall emphasis. It has all the resolution, speed and definition you will ever need, and the only thing you could say it lacks is a little bit of extra presence. I would hasten to add that FOR ME, this treble is tuned pretty much perfectly in line for my own listening preferences, but if you are a dyed-in-the-wool treble head, you may want to try before you buy if an ultra energetic upper end presentation is what you are after.

Power requirements and gear synergy

Given the presence of the now-ubiquitous Sonion EST drivers providing some of the high end, it will come as no surprise that the MEST Mk2 can suck up plenty of juice, with the current hungry drivers benefitting from a source that can kick out some decent output. It’s not a difficult IEM to drive by any means, but the internal design definitely means it appreciates a little bit of horsepower on tap from your portable or desktop source to really come alive.

With regards to synergy, the MEST isn’t particularly source-picky, the warmth and fullness in the middle of the sound on the Mk2 tends to make it fairly understanding when it comes to playing back music that is less than ideal, or when playing from a source that is a little crispy or harsh. Given the level of resolution the MEST is capable of, you ideally want to be pairing it with something that has plenty of technical capability, as this is an IEM that can really make the most of any additional detail you want to throw at it. It’s not warm enough on its own to suggest avoiding ultra-warm DAPs like the Sony WM-series, but for my preferences it worked better with the clean and crisp balanced output of the DX300 compared to the warmer tube stage of the Cayin N8. It’s definitely a case of preference rather than better or worse here.

Comparisons

Unique Melody MEST (Mk1)

I wrote a whole separate article comparing these two here

IMR Acoustics Elan – (Hybrid; 1xDD, 1xBone Conduction, c. $840 before discount)

The Elan is the latest model from the prolific UK based manufacturer IMR, and unusually for the company, will form one of their “stock” models for the foreseeable future. Also unusual is the fact that the Elan also uses a bone conduction driver to deliver some areas of the sound, putting IMR in the very small bracket of IEM makers that are using this new driver tech for proper “audiophile grade” in-ears.

In terms of configuration, the Elan is a simpler dual-hybrid design compared to the MEST, with one high magnetic-flux 10mm carbon-nanotube diaphragm dynamic driver (with an amorphous diamond-like carbon coating running across the full range and a single bone conduction driver wired into the chassis. The IEM body is made from machined aluminium, with a smaller footprint than the MEST, hugging the inner ear quite well and sitting a lot lower in profile in the ear. The metal chassis is anodised in a nice Matt black, with three tiny crimson red torx screws on the circular faceplate and a small IMR logo on the stem of the IEMs the only visible adornments to an otherwise all-black visual aesthetic. In terms of construction, the Elan looks good (if you like the same sort of industrial design elements that brands like Acoustune made famous), but probably a little understated compared to the more elegant carbon fibre and gold elements of the MEST. Fit-wise, the MEST slots more snugly into the contours of the inner ear with its pseudo-custom shape, whereas the Elan is a well fitting but more traditional IEM shape, so doesn’t hug the ear quite as tightly.

In terms of accessories, the Elan keeps pace with the MEST for the most part, throwing plenty of tips and two carry cases at the owner, along with a 6.3mm adapter and three (yes, three) different IEM cables in 3.5mm SE / 2.5mm balanced / 4.4mm balanced. Where the MEST shows the additional price tag is in the fit and finish of the case and cable, with the OCC cables of the IMR model looking and feeling nice, but not quite as high end in feel as the far pricier PW Audio copper model that comes with the MEST. Similarly for the case, the IMR load out is probably more practical, but just lacks a little bling compared to the bespoke Dignis leather affair included by Unique Melody. The IMR model definitely doesn’t leave anything to be desired, but given the price differential, you can see a difference in the quality of accessories.

Tuning wise, it will be slightly difficult to pigeon-hole the Elan, given that it is at tunable IEM with more 48 (!) different filter combinactions. For the sake of everyone’s sanity, I have stuck to one of the three “recommended” filter combos suggested by IMR (grey base filter, blue end filter). This happens to be my favourite in any case, but is tuned for “high clarity and resolution, with a clear midrange” according to the IMR user manual. This gives the IEM a tuning that is somewhere between V and W shaped, with a push in the bass and treble, but a nicely forward midrange to keep the instruments and vocals from getting buried in the mix.

Starting with the bass, IMR are known for producing IEMs that re immensely “bass capable”, and the Elan doesn’t veer from that established house sound. The 10mm CNT/ADLC dynamic driver kicks out a serious amount of bass volume and slam, pushing CA Atlas volumes of decibellage and air. They are immediately warmer and thicker in the low end than the MEST, with more mid-bass presence and slightly more sub-bass. Extension and speed are similar, with both DDs presenting a very technically capable low end, more akin to a BA type setup. The Elan hits deeper and harder than the MEST, with a fuller sounding bass note and slightly longer decay.

Technically, both are excellent examples of DD tuning, but the Elan probably shade the MEST slightly in terms of raw texture, which surprised me. Listening to “Palladio” by Escala, the texture in the opening cello is crystal clear on both IEMs, but just sounds a little more forward and weighty on the Elan, compared to the slightly airier and leaner MEST.

Presentation-wise, the bass fills a lot more of the lower stage area on the IMR model, adding a warmer sheen to the music being played and providing a slightly “grander” backdrop in terms of note size. If you are averse to north of neutral bass then the MEST is definitely the closer of the two to a more “pure audiophile” type tuning with its flatter mid bass, but if you prefer a thicker, weightier bottom end to your sound tuning then the Elan would be my recommendation here. Playing devil’s advocate, you could tune the bass on the Elan down a few notches using the more vented filters, but this has the effect of sucling out the body of the sound, but doesn’t really add much in terms of technicality or speed, so is a step backwards versus the MEST in my opinion.

Mids are more similar than different on these two models, the Elan packing in plenty of textural information and resolution, managing to stay a step clear of the large bass underneath. This is where the bone conduction drivers start really contributing to both IEMs, so it probably isn’t that surprising. The Elan sounds the fuller and more forward of the two, with the MEST coming across as thinner and slightly cooler in direct comparison, but still in a similar “W” shaped configuration like the Elan.

Playing “Lights Of My Hometown” by Brantley Gilbert, the vocal sounds fatter and more forward, and somehow seems to reach a little deeper than the MEST. It’s difficult to quantify, but the vocal presentation seems larger, so the notes reach “in” to the stage a little, compared to the more distant (comparatively) positioning of the UM quad-brid. This is balanced off with a greater sense of air and separation on the MEST, which feels notably more spacious due to the smaller instrument size (again, comparatively – the MEST is certainly not a small or distant sounding IEM).

Detail in the midrange is a lot closer than I would expect, but just edged by the MEST, with the additional air on the stage allowing for the more subtle details of a track to be more readily noticeable.

Treble follows suit with the midrange, with the Elan presenting notes in a thicker manner compared to the MEST, with a little edge of sharpness to the sound. The MEST has the classic EST treble – effortless and weighty, and puts a little more “roundness” into the presentation without losing any definition. Again, detail is close between the two models, but the MEST shows the benefit of its combination of BA, bone conduction and EST drivers here, providing a sound that is slightly more ethereal and slightly more defined at the same time. The Elan will appeal to people looking for a zippier, sharper cutting edge to their top end, but in terms of quality it comes off an honourable second to the excellent UM model here for pure detail and tone.

Separation and layering is excellent on both, but the MEST presentation naturally spaces the instrumentation further apart, giving a greater feel of air. If you prefer a well defined but closely packed “wall of sound” style presentation, the Elan will lean more towards your preference – if you are looking for a more spacious and expanded stage, the MEST is the choice here. Imaging is excellent on both IEMs.

Overall, the Elan comes a lot closer to the sound and quality of the MEST Mk2 than I was initially expecting, given it costs almost 50% less. Both make excellent use of the new bone conduction driver tech to present music with a slice of added “realism” that becomes quite addictive when you try and move back to other IEMs afterwards. This one will come down to preference as much as performance – if you are looking for a tweakable IEM with plenty of high quality bass and a fat, large sound that doesn’t sacrifice punch or detail, the Elan pushes ahead of the MEST. If you are looking for something with that dash of extra refinement and ultra-detail across the board and a lighter, more expanded sound (that still isn’t bass-light), the MEST would be my recommendation.

IMR Acoustics Elysium – (Hybrid; 1x10mm DD, 1x12mm Planar, 1xBone conduction, c. $1100 before any discount)

Not content with comparing against one other bone conducting IEM, I thought I’d throw in another IMR comparison from another one of their recent special releases that uses the new bone conduction drivers. This time round it’s their Elysium model (no relation to the Vision Ears tri-brid flagship). To make things nice and simple, the Elysium shares exactly the same accessories and shell design as the Elan, apart from having a polished aluminium colourway. It also offers the same tunable nozzle system, giving over 40 different flavours of sound. For simplicity, I have used the same filter setup for this comparison as the Elan comparison above, going for a slightly boosted bass and treble to give a reasonably W-shaped tuning.

Stepping straight to the sound, the Elysium is a smoother and more analogue sounding IEM compared to its cheaper sibling. It uses a different dynamic driver (a “normal” ADLC coated dynamic rather than a CNT-based one), but supplements that with a large 12mm planar magnetic driver to sit alongside the bone conduction motor. In terms of bass, the dual drivers present plenty of punch, presenting more quantity in both mid and sub bass than the MEST, but this time not quite keeping up with the texture of the UM model. There is a more laid back analogue tone to the bass, with a slightly longer decay to bass drum hits and bass guitar notes compared to the tighter MEST presentation.

Moving up to the mids, there is a clearer difference here, both in presentation and resolution. The Elysium is smoother and more velvety, with a stage presentation that doesn’t feel as deep as either the Elan or the MEST. Notes feel almost veiled in comparison to the sharper, thinner and more defined MEST – there is still a good amount of detail being presented by the Elysium, but it almost feels like the difference between listening to vinyl and to a CD. The IMR model is going for a fatter, more romantic sound that pulls the notes closer together on the stage and paints everything with a warmer timbre, compared to the crisp and Ultra-HD presentation of the MEST. Where the Elysium does excel is in the tonality of the mids, with the rich velvety tuning of the IEM really suiting classic rock and blues style recordings.

Treble follows a similar pattern, with the Elysium giving a thicker and darker sound to the treble than either the Elan or the MEST. Notes are weightier, carrying some of the more effortless feel of the MEST (probably due to the planar driver), but not feeling quite as refined as the EST-driven UM model as you climb into the higher end of the tuning range. Again, this is as much a tuning choice as a technical capability, with the darker and more analogue tuning across the board for the Elysium (with my particular filter choice, obviously) contrasting with the airier and more delicate MEST. If you are a treble-head, the MEST would be the logical choice here, unless you really prefer a darker, more rolled off sounding treble tuning.

Technicalities are similar to the Elan, but a small notch lower due to the tuning, so suffice to say the MEST holds a slight edge here. The only area where the Elysium really excels is in the separation and layering aspect – it may not present the crispest of sounds in comparison to the other two, but it is able to pull the music apart at a macro-detail level so that everything can be neatly and easily followed in the ear. It is also noticeably wider than the MEST, giving a far more extreme left/right separation on tracks like Trouble by Ray Lamontagne, pushing the hard-panned drums and bass guitar so far to the left and right they almost fall off the stage.

Interestingly, the chief designer at IMR has confirmed that the bone conduction driver on the Elysium is less effective than the Elan, even though the shell design and placement is the same – I believe the large 12mm planar DD has something to do with that. This may account for the different tonality and technicality, but the Elysium still manages to pull off that bone conduction “realism” that the other two BC models I’ve heard so far have in spades, so it’s only a light differential to my ears.

This one is an easier recommendation; the Elysium is tuned for a specific type of sound, so unless a wide soundstage and classic analogue tonality are your two key requirements, the MEST provides a sharper, cleaner sound at a similar price. These two IEMs are definitely more complementary rather than competing in my eyes (or ears).

Ambient Acoustics MAD24 – (24xBA in a crossover less setup, c. $3500)

This may seem like an unusual comparison given the price difference, but the MAD24 from Ambient Acoustics is sufficiently unusual for an all-BA in-ear to warrant putting up against the current poster-child for “new” IEM driver technologies.

The MAD24 is a crossover less design, employing 24 armatures in a uniquely designed interior shell that employs different porting and sound bore designs to mechanically control the different frequencies rather than using a traditional electronic crossover. Given the nature of the design, the MAD24 is actually surprisingly coherent, going for a rich and ultra-thick tuning that is definitely more musical than reference.

Starting with the packaging and design, the MAD24 comes in a nicely designed presentation box with plenty of technical specs and line drawings on the outside. It doesn’t scream luxury (which it probably should at the asking price), but it definitely looks like a professional presentation. The kit out and accessories are similar to the MEST, with a small puck-shaped faux-leather carry case, a multi-core copper cable and a small selection of tips in a metal capsule designed to be hung from a belt or set of keys. The case isn’t quite as high quality as the Dignis case, and the cable definitely feels a couple of notches down the price tier compared to the PW Audio model included with the UM model. The MAD24 certainly isn’t poorly equipped, but just lacks a little in terms of fit and finish compared to the MEST accessories.

The IEM itself is pretty chunky in size (as you’d expect from a 24(!) driver model, following a similar pseudo-custom shell design as the MEST but being appreciably bigger along all axes. I’d estimate the MAD24 is probably about 30% larger than the MEST, and while it fits pretty impeccably for my large ears, it isn’t quite as ergonomic or snug feeling as the UM model. Cosmetically, the MAD24 looks beautifully made, with a nicely three-dimensional effect to the purple abalone-style faceplate and a perfectly smooth and blemish-free shell. In direct comparison, the MEST is more visually appealing with its mix of carbon fibre and gold flecks, but the MAD24 certainly isn’t an ugly looking IEM.

Moving on to the important bit, the sound these two IEMs produce is pretty different. The MAD24 goes for a thick, rich sound that is warm and enveloping in comparison to the cleaner and thinner sounding MEST. Starting with the bass, the MAD24 pushes a few more dB in the lower end than the MAD24, with more of a mid-bass presence than the UM model. Extension down low is similar, with the MEST having a slight edge in terms of physical slam due to the hybrid design, but the MAD24 pushing a surprising amount of air with its quad-BA low end sent up. The MAD24 definitely feels more powerful, but that power comes at the cost of a little obvious texture and cleanliness compared to the unique Melody quad-brid. The MAD24 definitely doesn’t lack for layering, but separation is slightly less apparent down low, with the bass lines presenting in a more physically powerful way but without as much audible texture around each note.

This highlights one of the unusual aspects of the MAD24 – even though the MEST Mk2 presents a cleaner tone and more immediately impressive technicality to the low end, when you dig into the sound and really listen, the MAD24 actually beats out the MEST in raw detail retrieval and resolution. It pulls more tiny micro-plankton out of the notes, but doesn’t push it into the forefront of the stage, preferring to saturate the sound with barely audible additional layers of resolution. It sounds like a cop out to say that this is an IEM that requires some “brain burn in”, but when compared over a longer period, the additional capability of the Ambient Acoustics flagship in the lower end becomes apparent.

Moving up to the midrange, it’s a similar story. The Mk2 is definitely leaner and more raw in comparison to the thick, meaty sound coming out of the 8 (!) mid range armatures in the MAD24. Guitar strums sound thin and crisp, hanging in plenty of space, and emphasising the reverb of strings and gentle scuffs on tracks like Shelter (again by Ray Lamontagne). In contrast, the MAD24 immediately feels warmer and more suffused, the much greater bass filling the air around the resonating guitar chords. Lamontagne’s voice feels richer and more velvety on the Ambient model, without sacrificing anything in the way of texture. On its own, the MEST presents a fantastic midrange, but in comparison it feels quite thin against the solidity of the Ukrainian flagship.

The MEST is excellent at presenting mids in a raw and detailed fashion, whereas the MAD24 goes for a much fatter and thicker sound to guitars and piano, providing a bit more of an emotional and warmer sound. The MEST feels like it is surrounding you with nicely spaced out streams of musical information like a good waterfall shower, whereas the MAD24 feels more like being hit by a tidal wave (if you could see every drop of water in the wave as it approached). Bottom line – if you prefer a more neutral or lean tune to your midrange voices and instrumentation, the MEST is the model for you. If you need detail, but don’t mind thickness and body, the MAD24 is again slightly ahead in the usual technical metrics, as well as capturing that rare emotional aspect to the sound to sit alongside the raw power on display.

Treble is VERY different between the two models, with the MEST again providing the cleaner and clearer initial impression, with a smooth and effortless sound that feels light and crisp in the ears, in comparison to the more laid back and less emphasised tuning of the MAD24. The Ambient flagship goes for a less forward top end sound, still packing in plenty of flagship level detail into the presentation but pulling things a little closer in and sounding a little more dense and physically solid. It’s the sort of treble tuning favoured by people who like clear and clean treble rather than zingy or sparkling – there is no sense of claustrophobia or lack of stage size on the Ambient model, but it just doesn’t feel as airy and spacious as the MEST. Personally, I actually prefer the turning of the MAD24 here, as it aligns closer to my personal preference. There genuinely isn’t much between the two with regards to detail or resolving capability (with the MAD24 coming out on top, despite its relatively darker tuning), so this is 100% a preference call as to which is better.

Timbre differs a little between the two models, with the UM in-ear shooting for a more stylised, musical sort of presentation in comparison to the more natural sounding MAD24. There is no doubt that the AA model sounds the more accurate and “real” of the two IEMs, so if that is a consideration for you, then Ambient definitely have the edge here. To counter, the MEST does have the current “driver du jour” in its bone conduction drivers. This adds a very difficult to quantify but easier to feel sense of reality to the sonic presentation compared to the MAD24, the BC drivers putting back some of that “sat in the front row” sort of feel in the inner ear, where you feel the track with your whole head, not just your ears. It isn’t quite as rounded and holographic in presentation as the MAD24, but in terms of uniqueness, the MEST is hard to fault or compare with here.

Overall, it comes down to price and preference to pick these two apart. It’s fair to say that I consider the MEST Mk2 as probably THE best price-to-performance IEM in the current “flagship” market, and one that I absolutely love in terms of both tuning and performance. It’s a stellar IEM, and one with very few flaws. The problem with hearing the MAD24 is that I think the MAD24 is both subjectively and objectively better. The notes are thicker and more realistic, the detail is slightly better across the board, and the staging is truly holographic. Each area on its own is only a marginal improvement over the MEST, but taken together, once you get the MAD24 to click, it is an addictive sound that makes other top tier IEMs sound thin and a little lifeless in direct comparison. Price is obviously a consideration here: if you are looking for a high performing IEM without taking out a mortgage, the MEST will tick all the boxes you think you will ever need. If you can justify adding an extra $2000 to your bill, the MAD24 will take you just a little further up that audio hill to the mythical destination of “endgame”.

Conclusions

As mentioned above, my opinion of the MEST Mk2 is pretty simple: it is hands down THE BEST in-ear monitor I have heard at its price bracket yet. The usual caveats apply – if you aren’t a fan of guitar based music and orchestral soundtracks in their early forties with ears seasoned by years of live concerts, you may not agree. For those who do share my preferences, this really is a taste of top-tier excellence at an expensive but manageable price, especially compared to the stratospheric RRPs of some of the other major brands flagship IEMs at the moment. It has detail in spades, an engaging and musical sound, beautiful design and accessories and a dash of something unique thanks to the bone conduction element that really pulls you into the sound.

These skirt close to scoring a perfect 5 across the board, only losing marks for usability given the incredibly tip-sensitive nature of these IEMs, and the need to get an ultra-deep fit to get the best out of them. I’m a huge fan of innovation in audio, and I think UM have genuinely pushed the market forward significantly with their design and implementation of this in-ear monitor. Stunning stuff.