Ambient Acoustics – 24 types of madness


Ambient Acoustics was set up in 2009 in the Ukraine, primarily to service the professional audio and hearing aid markets. They started getting a little notice in audiophile circles a few years ago with their LAM serious of tuneable switch models, and it’s fair to say they are a brand that is now starting to gather some decent recognition in the audiophile landscape in 2021. This is mainly due to the release of their Main Audio Destination (MAD for short) series of in-ears. These models are all balanced armature designs, ranging from two armatures per ear at the entry level to a whopping 24 armatures per side (a record for an in-ear design as of time of writing).

Not content to just pack in the drivers, Ambient are also pioneering some interesting technology in their new designs, with a zero(!) crossover design, linear phase and a few proprietary technologies like their ANOR acoustic notch filters and a pressure reduction system called SOER. Overall, a very interesting company, and definitely one that isn’t afraid to push the boundaries of what is possible with current driver technology.


I would like to thank the team at Ambient Acoustics for organising the UK and European tour for the MAD16 and MAD24, and for my fellow reviewer Skedra over at the Viking Audio Blog for convincing me I needed to hear these IEMs. I had both IEMs in my possession for a couple of weeks before the tour package had to be sent on to the next recipient – no incentives (financial or otherwise) were sought or received for writing this review, and all the opinions contained within (however misguided!) are entirely my own.

Build and ergonomics

The MAD24 is designed as a custom IEM first and foremost, so talking about the design of the universal models is probably a bit of a moot point. That being said, the design that Ambient have gone with is actually pretty attractive, with a dual-tone colourway that sports the usual shiny black acrylic inner face common on most non-metallic IEMs these days, and a more interesting milled faceplate in a sort of purple mother-of-pearl style design.

The shells themselves are pretty massive, as you’d imagine for an IEM that houses 24 (!!) balanced armatures on each side. AA have gone for a simple semi-hemispherical shape on the outer face, with nicely rounded edges and an inoffensive overall shape, the face being perfectly flat. The inner face of the IEM is contoured in the now commonplace pseudo-custom style, with a protruding “wing” at the top to lock into the concha of the upper ear, and a nicely angled nozzle that allows for a pretty good deep insertion (for my admittedly larger than average ears, anyway). There is no getting around the fact that these are very large IEM shells, with a depth of around an inch, giving them a true JH Audio OG model type feel (also referred to in some circles as the Frankenbolt look). So, the universal model may not suit people with a particularly small or shallow inner ear – as mentioned, as the intended audience for these is the custom IEM user, that probably won’t cause too much undue concern at Ambient HQ.

For me, fit and isolation are excellent once you have found the correct tip choice (more on that in the relevant section below). These are IEMs that I can comfortably wear for hours without any issue or hotspots, and that stay firmly locked and sealed in the ear with mild to moderate movement. They may be big, but they are very well-considered, so no criticism from me on that score.

Unboxing and accessories

The MAD24 comes in a fairly well designed (if a bit utilitarian) cardboard presentation box, with plenty of technical specs and blown-up diagrams adorning the various sides, and a nice glossy pic of the IEMs themselves on the front of the box. Opening up, the inner cardboard box unfolds to reveal a classic “custom IEM” unboxing, with just the IEMs and the carry case embedded in a foam layer. The carry case is circular and looks to me made of a heavy-duty synthetic leather – popping that open reveals a desiccant pellet, branded cleaning cloth and 6.3mm jack adapter and a small metal pellet case on a keychain that unscrews to reveal the included ear tips.

The included cable is an ultra-soft copper cable in an 8-core design. There is a nice bit of branding on the small black metal y-splitter and a standard chrome and carbon fibre barrel to the 3.5mm connector, but apart from that, it screams more “AliExpress upgrade cable” than high-end cable collaboration, which seems to be the norm for the big headline IEMs in the current market. That holds true for the rest of the accessories and presentation – this is perfectly functional (and in the case of the IEM case, actually pretty well designed), but it doesn’t particularly give the impression of opulence or luxury, which you will find with some of the OTT unboxing experiences and accessory load outs on other $3500+ flagships from the other big in-ear manufacturers nowadays. As a company, it looks like Ambient Acoustics are still geared more towards the functional “stage CIEM” style of presentation, rather than the pretty-pretty or “added value” style load outs of the more consumer audiophile – that is definitely something that can be improved for future revisions.

Initial impressions on sound

The tuning of the MAD24 is pretty unusual for a TOTL IEM, and follows pretty closely in line with the physical design: it’s BIG. My initial thoughts on what a 24-driver in ear would sound like were pretty much along the lines of “just how analytical can they make something without actually cutting your eardrums when you fire it up”. What actually poured out of the tri-bore design of the MAD24 was more akin to an avalanche of sound. It is without doubt the most solid feeling IEM I’ve ever come across. Bass is thick and forceful, sounding almost like dynamic driver bass in intensity and punch. The emphasis is more towards mid-bass than sub-bass in the low end, but the extension is pretty plentiful when required.

Midrange is forward and dense, like some sort of sonic version of a chocolate ganache. Everything is packed pretty close together, but still manages to resolve into its own area of space without bleeding or masking. Stringed instruments sound very rich and full bodied, with a very large note size. Scale is a word that springs to mind – once you find the right tips to unlock the MAD24, everything just sounds massive. Texture and fine detail is audible around the fringes of guitar strums and vocal inflections, but not pushed massively forward. in fact, on first listen you can be fooled into thinking this is a thick and syrupy sort of tuning, until your ears zero in on the fact that the detail is still there. All of it. It’s an unusual sound, but a pretty damn addictive one once you get used to it.

Treble is similar in both position and size, presenting in a smooth but detailed manner. This is NOT a bright sounding monitor, but it doesn’t feel like it lacks for headroom either. It almost apes the typical qualities of an EST style driver setup, with plenty of detail but without sharpness or harshness. Given the raw power of the frequencies underneath, the treble can feel a little delicate and not quite as forceful or emphasised in comparison. I imagine this won’t be a great recommendation if your preferred sound signature is bright and crunchy or you need bags of air in the top end of your soundscapes, but technically there is plenty of resolution and clarity to dig into. For my preferences (smooth and clear treble that site behind the mids and bass) it’s pretty close to my ideal curve.

In summary, the MAD24 throws out a sound that is somewhere between XXX and XXx in terms of bass/mids/treble. It feels balanced, but also as if all the frequency bands have been pushed forward on the equaliser, to present a sound that is just epic is size and weight of note. Detail is abundant, but rendered naturally without sharpening or trickery, and not pushed up front in the presentation. It’s a bold tuning approach to take, but it’s nice to hear a brand taking the musical approach with their flagship in-ears without sacrificing the technical chops in the process.


Starting with the sub-bass, the MAD24 presents good extension down into the deep sub-bass region, digging as deep as the track requires without any real sense of “roll off” as the frequency drops down. It isn’t an absolute sub-bass monster, but there is enough sense of rumble down low in tracks like “Disc Wars” from the Tron Legacy soundtrack to give the track a decent sense of gravitas and weight. The quad-BA array that Ambient are using for the MAD24 is pretty punchy, but still has all the usual hallmarks of an armature-driven sound, so this IEM won’t be able to push the same level of air and physical vibration that you get from top-tier dynamic driver or planar dynamic sets.

Moving up to mid-bass, things start to pick up a bit in terms of emphasis, with the MAD24 carrying more mid-bass quantity. It is a fairly broad raise, without a specific “thumb” or peak, rising pretty uniformly through the mid and upper bass regions until you hit the midrange. This is where the sound starts to deviate from the more traditional BA style of bass, with the MAD24 putting out a big, fat sound that carries a LOT of punch and weight. Bass is quick and articulate, but it’s fair to say it also slams probably as hard as anything I’ve heard that doesn’t have a dynamic or planar driver producing it. There is a real sense of visceral physical presence to bass guitars and kick drums that gives the MAD24 a very dynamic flavour to the low end.

“Bad Rain” by Slash absolutely blasts into the ears from these IEMs, the kick drum beat that starts the track hitting with real slam and punch, and when the distorted bass guitar kicks in at the 23 second mark, the MAD24 captures the aggression in the track perfectly. The bass guitar sounds textured and raw, with he resonating strings hitting hard and deep, the main body of the note feeling fat and heavy, with plenty of texture. Some IEMs maintain the textural information by leaning back on the weight and body, but the Ambient flagship manages to paint plenty of information on the fringes of the sound without losing the heft and sheer size of the presentation. This is where the “wall of sound” style that the MAD24 has been tuned with starts to become apparent – everything in the lower end of the soundscape sounds BIG, but still has plenty of crispness and control.

Looking for a bit more smoothness and liquidity, “Hello, It’s Me” by Sister Hazel is up next on my review playlist. The MAD24 handles it well, the liquid bass line that kicks off proceedings sounding wet and weighty rather than stiff or chalky like it can on some IEMs with a tight grip on the bass, but still pushing lots of fine detail out as the bass strings reverberate and the slinky riff winds through the track. “You’ve Lost That Lovin’ Feeling” by Elvis and the Royal Philharmonic is another great tester for texture and liquidity in the low end, and the MAD24 unsurprisingly makes short work of this too. The bass guitar sounds like velvet dipped in chocolate, with plenty of presence but not intruding on the orchestral arrangements around it. The MAD24 gives an almost “equal loudness” feeling to this track in terms of the contour of the sound, with the bass sounding big and plentiful, but sitting in line with the equally large and emphasised vocals from The King.

Overall, the bass tuning is unexpected for an allegedly reference-tuned flagship, but once you get used to the sheer quantity and weight, it is very well judged. There is enough sub-bass quantity to ensure extension isn’t a problem, and to round out the underneath of the larger bass lines that sit above. Mid bass is almost at live gig levels of loudness in some tracks, but it all presents with such tightness and control (along with bags of detail) that it doesn’t feel like overwhelming the rest of the sound. It gives the whole sound a large and substantial foundation, and will play well with people who like reference tunings and closet or fully-fledged bass heads as well.

This isn’t a bass presentation that lays out the low end in hugely separated fashion, preferring to push the size of each element up to maximum and stack it all together neatly in the ear like a reigning Tetris champion. Despite that, the technical chops mean that each element is clear and more importantly, clearly defined in the sonic landscape, presenting a bass that is both coherent and pretty damn musical at the same time. In fact, I’d hazard a guess that the only people who won’t like the MAD24 low end are either the hardcore HD800 ear-rapier crowd or those who only listen to acoustic busking or chamber music on their playlists.


The mids transition smoothly from the bass region, with no bleed or blurring from underneath. Like the low end, they are stage-forward in presentation, pushed forward to the listener’s ear in a similarly intimate “stage tuning” favoured by brands like JH Audio. They retain a grand sense of scale despite the intimacy, mainly by sheer size of the notes. Instrumentation and vocals sound absolutely huge for an in-ear, painting a large sonic image around the head of the listener that places you right in the middle of the soundscape.

Tonality-wise, the MAD24 are a moderately warm and rich sounding IEM, with an organic sheen to guitars and other midrange instruments that makes them sound almost euphonic. This isn’t a classic analytic style tuning, the MAD24 doubling down again on weight and body of each note rather than emphasising the edges. That isn’t to say that the sound is in any way blunted or blurry – the MAD24 packs an unexpected amount of flagship-level detail around the heft, giving the IEMs a non fatiguing but extremely resolving sound that takes a little adjusting to. It achieves its resolution via the blackness of the background, and the excellent layering and separation of each strand of music.

Tracks like “In Love With The Pain” by Black Stone Cherry demonstrate that quite well, the fat guitar tones that drive the song sitting underneath an acoustic guitar refrain that blends together beautifully without losing definition. Some of my mid to top tier IEMs have trouble with this track, either losing the distinctive fatness of the main riff, or burying the jangling acoustic strings too deep in the wall of sound. The MAD24 treads a nice line here, keeping that distinctive wall of sound that the band do so well, but pulling the individual strands just far enough out to get the detail as well. It’s the sort of laid-back or effortless resolution that the Empire Ears Zeus was famous for, which gives a good indication of where I place the Ambient model in terms of detail.

Sticking with rock music, a few testers for speed and bite are up next on the review playlist: “World On Fire” and “Shadow Life” by Slash. Both tracks fairly rip along on the MAD24, with the 16 mid-range armatures keeping things crisp and crunchy as the staccato riffing fills the soundstage. Again, it doesn’t forsake body, so there is an almost tube-like sense of warmth to the guitar reproduction that makes it sound fat and spiky at the same time. If you like your rock guitar jagged and razor-sharp then the MAD24 will probably feel a little too “full” for your tastes, but if you want the speed and crispness of a leaner IEM with the heft of a warmer, fuller model, the MAD24 provides a pretty good balance.

Moving onto slower fare, “Since You Were Mine” by the Shinedown duo of Smith & Myers showcases Brent Smith’s distinctive pipes well, placing the vocals in an echoing stage right at the front of your forehead and playing the reverberating piano melody with a beautifully accurate tone. The piano notes sound grand but still real – timbre is another area where the MAD24 does particularly well, giving instruments and voices a true-to-life sheen despite the slightly stylised warmth and forward staging.

Searching for sibilance and harshness, one of my usual go-to tracks is “Whiskey And You” by country troubadour Chris Stapleton. To be generous, this sparse acoustic track sounds like it was mixed in a sack full of broken glass and razor blades in some sections, but the MAD24 handles it well. The harshness in Stapleton’s voice is apparent around the 1:45 mark, but it doesn’t tip over into an unpleasant listening experience. The Ambient IEM manages to pack enough roundness behind the raw edges to soften the vocal to a dull roar. In contrast, it does a phenomenal job of picking up the subtle room noises and creak of the guitar and stool at various points through the track. Again, resolution without rawness, which seems to be a common theme.

Another good stress tester of a track is “Starlight” by Slash and Myles Kennedy – the super-high vocal and harmonic-heavy guitar intro are both prone to harshness, but again the MAD24 comes through with no problems. The guitar tone is superb on this track, with a real sense of emotion as well as a nice cutting edge. Kennedy’s vocals are front and centre (actually a little left of centre in my head), soaring up as the song winds up into the chorus but again skirting around sibilance. I’ve heard this track on pretty much every piece of music reproduction gear I own, and it’s probably a little hyperbolic to state that I don’t think I’ve heard it sound any better, but it’s also true. The MAD24 has something genuinely special going on with the midrange, and this track really captures it.

Overall, the mids are the star of this particular show, packing an ultra-dense and physical portrayal of your favourite tracks and genuine top-tier resolution capability. To my ears, there aren’t any of the usual telltale dips or sculpted gaps in the frequency response to emphasise certain aspects of the music, with Ambient having the confidence to let the drivers and configuration offer up everything in the sound without compromise. Tonality is slightly warm but oh-so organic and inviting, and more importantly true to life – this is an IEM that sounds like a good pair of speaker cranked up to unwise volumes then put down about 10 feet in front of you rather than two tiny music playback devices jammed in your ear canals. The only criticism I can probably levy is that this isn’t a complete all-rounder; if your tastes run to a lean and crisp presentation, or you prefer your mids served up a lot farther back on the stage, the MAD24 won’t be for you. If you like your midrange meaty and emotive and front and centre of the sound, it’s a bit of a no brainier here.


As mentioned previously, the treble presentation is smooth yet extremely detailed, and to me feels like it just pulls a shade behind the other two frequency ranges in terms of stage position and emphasis. There is absolutely zero fatigue to the treble playback, with the MAD24 being able to be worn or hours without discomfort (as long as you can fit the large shells in your ear for that long, of course).

Violins sound exquisite, “Chi Mai” by the classical duo Duel fills the stage with haunting vibrato as the notes sweep around the stage, supported by some classic 80s style twinkling synth in the background. There is plenty of air to the sound, with a nice open space to the imagined stage rather than a “ceiling”. Electronics and other synth-heavy genres have the requisite sense of sparkle to the upper end to engage the ears, but this isn’t on the Campfire Audio Andromeda end of the treble scale, the MAD24 remaining more smooth and grounded.

Cymbals are crisp and decay naturally, with just the right amount of ring and bite. Not over-emphasised or too metallic, the driving percussion in tracks like “When Angels Learn To Fly” by Black Stone Cherry sits nicely on top of the track, carrying just enough weight to cut through the thickness of the sound underneath. Again, these won’t be the most emphasised treble monsters you will ever hear, so if you prefer hearing your cymbal crashes right at the forefront of the sound then the MAD24 will probably lack a little bite, but the more laid back and delicate tone works very well for my personal preferences. Speed in the top end is excellent, the MAD24 keeping pace with pretty much anything I threw at it without losing crispness or cohesion.

Extension is excellent, with the Ambient flagship pushing up further than my slightly aged ears can hear without loss of power or roll-off. It isn’t the most forward treble you’ll hear, but it doesn’t pull any punches or roll off early either, laying out all the information in the upper end clearly and concisely. I have to admit that my treble preference leans more towards clear and smooth rather than sparkling and glittery, and the MAD24 pretty much nails it right in the middle of my personal Goldilocks zone.

Tip choice

Ambient include a nice metal carry case and a small selection of tips to work through as part of the package. Unfortunately, not a single one of the stock tips was able to get the true performance levels of this IEM to appear in my ears. in fact, after listening to the MAD24 for a day with the stock tips, I was very much unimpressed with the overall sound. It’s no exaggeration to say that this is an IEM that is ultra-dependent on finding the right ear tips in order to get the best performance. It is more delicate than even the notoriously picky oBravo Cupid and Unique Melody MEST in that regard – you have to tip roll to get the most out of these bad boys.

As a reviewer, I’m loathe to write the phrase “night and day”, but it genuinely applies here. After working through pretty much every tip in my collection box, I settled on some “Audiophile” silicone tips from Flare Audio. These are a horn-bored tip that expand outwards from the nozzle in a cone shape, basically sticking a horn on the end of your IEM nozzle, and keeping the nozzle completely open and unblocked into the ear. Once these tips were locked and loaded, the staging and note size of the MAD24 expanded massively in my ears, going from normal to damn-near huge in size. Once you find the tips that work for your particular ear canals, you’ll know it – there is no going back to the standard once you’ve heard what a decent tip can do on these monsters.

Everyone’s ear anatomy is different, but my recommendation for those wishing to shortcut their tip rolling journey with the universals is to start with something like the JVC Spiral Dot series, or any other wide bore tips. This is an IEM that seems to need room to breathe – as mentioned, the Flares Audiophile silicone tips were my go-to, but I’ve spoken to other members of the tour who swear by different tips like the Azla Crystal (the Xelastec were a decent but not mind blowing match for me) – experimentation is definitely the key here, but genuinely worth it.

Power and synergy

As I only had a couple of weeks with the MAD24, I didn’t have a huge amount of time to DAP-roll, preferring to stick them straight with my favourite playback devices. As such, the impressions above are based off equal time with the Ibasso DX300 and the Shanling M6 Pro (21) – both DAPs can push out a serious amount of voltage, but neither required anything more than a moderate amount of volume on low gain to push the MAD24 to full capacity. In my opinion, this is not an IEM that NEEDS power.

That being said, it IS an IEM that will scale with the output chain. It was noticeable that it pushed out a little more raw detail with both the M6 Pro (21) and DX300 compared to other DAPs I own like the Cayin N3 Pro – it has a pretty high ceiling for detail retrieval and resolution, so it pays to feed it with the most resolving source you can find if you want to get the most out of the 24 armature array inside.

In terms of synergy, the MAD24 is a warm neutral in-ear, so I probably wouldn’t recommend doubling down with an ultra-warm source. It will handle it fine, but something a little crisper and more laid back will most likely be a better complement to the MAD24’s core tuning. Between the M6 Pro (21) and the DX300, I actually preferred the Shanling DAP. The DX300 has the tiniest of edges in overall resolution, but the ultra grippy and more energetic sound of the Shanling pairs really well with the overall tuning of the MAD24 to give a more musical and physically “dense” feel to the sound, bringing out the best qualities of the Ambient model. In comparison, the DX300 feels a little more laid back or relaxed, taking a little anima out of the presentation – in this regard, the MAD24 is pretty “true to source” when it comes to transparency, should be pretty source-transparent.

Overall, this isn’t an IEM that will ruthlessly exploit low quality files or source components, but on the flip side, it will reward you handsomely if you feed it well. Given the $3499 asking price I’m guessing not many users will be intending to run it off their iPhone dongles, but it’s worth stating nonetheless.


Unique Melody MEST Mk 2 – (Quad-hybrid, c. $1499 – 1xDD, 3xBA, 2xEST, 1xBone Conduction drivers)

The MEST probably needs no introduction at the moment, given the serious amounts of praise and hype that have been thrown its way since the original MEST Mk1 model premiered over a year ago. It is a quad-hybrid, and the first major IEM manufacturer model to incorporate bone conduction drivers alongside the more standard DD/BA/EST tri-brid architecture. The Mk2 revision addressed all the major issues raised by listeners about the first version, putting out a refined and highly detailed sound in a very nice looking and nicely accessorised package.

Starting with the packaging and accessories, the MEST Mk2 comes in a small cardboard presentation box, containing an IEM case, the IEMs themselves plus a cable and an assortment of tips, along with a nice magnetic cable tidy and the usual registration card type documents. Where it differs from the MAD24 is in the fit and finish of the included load-out; the IEM case is a high quality two-tone leather style affair from Korean manufacturer Dignis, the cable is a sleek black affair from boutique cable manufacturer PW Audio (with bespoke branded connectors and splitters), and the tip load out includes a set of ultra-pricey Xelastec tips from AZLA.

In isolation, the items provided are pretty much identical, but the finish and presentation of each is a level up from the Ambient offering. The MEST cable in particular is a beautiful looking design, retailing for c. $500 if purchased separately from PW Audio. In this particular instance, even though the MEST costs less than half of the price of the Ambient model, you would guess it was the pricier of the two if you just looked at what came in the box. the MAD24 load out isn’t bad or low quality by any means, but the gentlemen (and/or women) at Ambient could definitely pick up a few pointers from the UM model in terms of presenting a package that “feels” expensive and packed with quality.

Fit-wise, it’s an easy win for the MEST – both IEMs are comfy in the ear, but the MEST is significantly smaller and more streamlined, fitting snugly in the ear with no fatigue or lack of comfort. It’s a small, neat design, and should make the MEST more of a universally acceptable fitting, rather than the quite frankly huge shells of the MAD model.

In terms of sound, the two IEMs offer up a very different tuning. The MEST Mk2 is a beautifully crisp, musical sound, with bags of air around each note and a solid but not hugely weighty presentation. Starting with the bass, the MEST has an excellent DD-driven low end, with more of a sub-bass tilt compared to the fuller and thicker mid-bass of the AA model. Quantity wise both models are relatively similar, with the MAD24 winning out as the MEST drops a little in the mid bass region. Quality wise it’s close, but the MAD24 manages to eke out just a little more detail and layering in the low end, without losing anything in terms of impact or physicality compared to the dynamic driver powering the unique Melody quad-brid. Neither are basshead monitors, but both excel at providing a tight, textured bass that is slightly north of neutral, with the MAD24 being perceived by me as being the slightly “heavier” of the two. Density of note is definitely shaded by the MAD24 here.

Moving up to the midrange, this is where the two models start to diverge slightly. The MEST midrange is ultra-clear, painting each note in an ocean of black space and giving just enough weight not to sound lean, but definitely not packing in any additional heft if it isn’t already in the track. The MAD24 midrange is a whole stack of phone books thicker (remember when those were a thing?). Density of note on the MAD24 makes the MEST feel positively flimsy in comparison, which is pretty impressive. Detail is similar between both models, with the MAD24 having a small but noticeable edge across the spectrum.

**Please note, for those that bulk at the use of the word “small” when describing differences between a $1.5k IEM and a $3.5k IEM: this is the law of diminishing returns writ large. Yes, there IS a noticeable difference in resolution and detail retrieval with the more expensive model, but the reality is it’s only a small jump up, given the relatively high level the MEST is already starting from. As mentioned earlier, I’m loathe to use phrases like night and day, as the reality is for IEMs of this sort of quality, the differences are always likely to be more small and subtle than big and glaring. Anyway, back to the scheduled programming…

One area where preference will definitely play a part in this comparison is where it comes to midrange separation and layering. The MEST peels all the notes wide apart, laying things out like a socially distant gathering of musical info. In contrast, the MAD24 keeps everything separate and layered, but it’s more like an onion. In fact, more like an onion that has been packed into a crowded tube train. Everything has its own defined space, but it is pushed up close and personal with all the other audio data. It’s a rich, dense sea of sound, so it will depend where your preferences lie – wide open and ultra-separate? The MEST wins out. Clearly layered but packed in tight? The MAD24 wins the vote. You pays your money and you takes your choice, as the phrase goes.

It’s a similar story for treble. The MEST is a fair bit more emphasised and zingy than the more genteel MAD24, with more bite to the EST-powered notes and a definite push forward on stage. Detail-wise, again it’s quite surprising that the MAD24 is probably the more detailed of the two in-ears, but it’s even closer than the midrange. Like bright and crisp treble with a nice lightness of note? It’s the MEST. Prefer smooth and rounded with more solidity? MAD24. These really are two very different beasts.

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 a second-generation bone conduction driver strapped to two carbon fibre plates on the IEM shell. This adds a very difficult to quantify but easier to feel sense of reality to the sonic presentation, 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.

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”.

Subjective impressions and comparisons

Given the short timeframe I had the MAD24 in my possession, I wasn’t able to spend the time comparing against my other IEMs in the sort of detail I usually like. The following impressions should therefore be taken with the requisite tonne of salt, as they are more like knee-jerk reactions to the perceived differences than a real, analytical comparison.

Empire Ears Zeus-XR – (14xBA, c. $2500 when originally released)

The Zeus-XR was the former Empire Ears flagship of their Olympus line, and former holder of the “most BAs in an in-ear” title around the time it was released. it is an all-BA flagship, with a tuning switch to change between a 7-way and 8-way crossover, to switch the tuning between the more musical original “Zeus-XIV” tuning and the more analytical “Zeus-R” revision that followed it.

Sonically, the Zeus is an ultra resolving monitor that is mainly centred around the mids and treble. Bass is punchy but light, and definitely errs on the lower end of neutral, even in the XIV setting. There really is no comparison in terms of quantity with the MAD24 – the Ambient model has more bass, presented in a much meatier and denser fashion, with more detail and texture. The Zeus bass isn’t lacking resolution, but it just falls a fair bit behind the overall sound pressure output the MAD model is capable of.

Mids-wise, the two IEMs are pretty similar. The Zeus has always been famous for its dense and emotive midrange, and it certainly doesn’t disappoint in this comparison. It is almost as full and dense as the MAD24, just feeling a little lighter in touch but more organic than the wall of sound put out by the 16 drivers in the Ambient flagship. One area where the Zeus surprisingly pulls ahead is in capturing the raw emotion of a track – if there is a better IEM for pulling the emotion out of female vocals, I’ve not heard it. Detail wise they are both well matched, with top tier resolution and clarity. Tonality wise, the Zeus is a slightly more sharp and vinegary sort of sound, fashioning a peak in the higher mids that gives the sound bite, compared to the more even-handed Ambient IEM.

Treble wise, the Zeus is more pronounced, with a heavier emphasis on the high end in terms of quantity. Quality is again similar, with the MAD24 possibly shading the Zeus detail-wise, although it was very difficult to tell. These are definitely two polar opposites here, as while the Zeus isn’t hot or spiky, it is definitely on the treble-heavy end of the spectrum compared to the MAD24. If you prefer a more sedate or laid Mack treble, the Ambient model will definitely be the better option, but if you crave emphasis in that high mid/lower treble range, the Zeus is probably going to be closer to your ideal curve.

Overall, both IEMs are detail monsters, but in a very different way. The Zeus is dense and emotive, with an ultra clean presentation but a lighter, snappier tone than the MAD24. It also carries a LOT less bass weight, so if you like your bass anything other than on the light side of neutral, the MAD24 is definitely the better option for you here. These are horses for courses, and while the Zeus is still a pretty special sounding IEM on many different levels, I think the MAD24 is subjectively the better of the two for my preferences, with a better balance and a richer, more musical sound. Oh, and it doesn’t hiss, whereas the Zeus famously hisses when plugged into thin air, let alone an amp or DAP.

JH Audio Jolene (4xDD 4xBA hybrid, c. $1800)

I only acquired the Jolene from a fellow reviewer (thanks, Mvvraz) shortly after I had to ship off the Ambient flagship to the next tour recipient, so I was unable to run a side by side comparison. These impressions are again very short, and based on the notes I took on both models to describe the differences. Please also note that the Jolene I’m using is a custom model, but thanks to the freakishly straight ear canals of the devious owner, they actually fit and seal perfectly for me with the addition of a small set of AZLA Xelastec tips, so please bear that in mind when reading this.

Totally, the two IEMs are probably more similar than different. Ironically, the MAD24 steers closer to the well established “house sound” of JH Audio than the Jolene, as the quad-DD hybrid model was developed during lockdown to appeal to a more “audiophile” market rather than the touring musician crowd that typically use Jerry Harvey designs.

Bass-wise, both models carry a similar emphasis (when the Jolene is at full-bore on the bass attenuator, which is the recommended setting). Neither are bona fide basshead models, but neither are they lacking. The Jolene packs a little more sense of slam than the MAD24, probably due to the double dynamic driver setup powering the low end. There I also a more sub-driven emphasis on the Jolene, tapering down slightly into the mid bass, in comparison to the mid-bass uplift of the AA model. General detailing and texture are similar, from memory – both are high achievers in this area, with the MAD24 probably feeling the “faster” of the two compared to the slower decay of the more traditional DD driven sound in the JH design.

The difference starts becoming more apparent in the mids, with the Jolene painting a cleaner and crisper sound than the dense MAD24, lunging more similar to the MEST in terms of spacing between the instruments and layers. It isn’t as thin as the MEST, but neither does it have the insane wall of sound effect of the Ambient 16-driver array either. Detail feels similar – if I had to guess, I’d say the MAD24 probably shades the Jolene in raw resolution. Again like the MEST, the Jolene paints the mids in a much cooler, cleaner space, so any detail pulled forward is a little easier to identify on a casual listen. The Jolene also benefits from a beautifully lifelike tonality courtesy of the two miniature dynamic drivers in the JH “D.O.M.E.” configuration. unexpectedly, it is the more true to life and less overtly “musical” of the two presentations, adding less colour to the overall sound than the Ambient flagship. One point to note: these two IEMs are possibly the best two releases in the current flagship market at presenting electric guitars – they really are both built to rock.

The Jolene shows more high end emphasis than the MAD24, with excellent extension and a nice sense of space and headroom. Again, detail feels similar, but again, I think the MAD24 may shade it under closer scrutiny (or at least it gave me that impression). Tonality is again true to life on the Jolene, and adds more bite and a crisper and brighter tone to the music without making it hot or aggressive.

Staging on both IEMs is fairly similar, which deserves a mention, as the Jolene paints a very broad and three dimensional stage. The MAD24 probably has a slight edge in holography and depth, but it will be only very slight, as the jolene is top tier here.

Overall, these two IEMs are two very different examples of how IEM technology has moved on in the last few years. Both packed to the gills with cool new designs, and both sounding exceptional. Again, the MAD24 probably wins for me if I had to choose a subjective “best” between the two, but the Jolene is really very close to my ideal preference in terms of tuning, and I can see some people preferring it over the Ambient IEM. Given it’s approximately half the price, that is a pretty bold statement.

Final thoughts

I genuinely didn’t think I’d end this review singing the praises of an IEM priced the same as a small second hand family car, but here we are. There is no getting around it, the MAD24 is a unique and sonically stellar sounding flagship, with something genuinely new to offer in the ever more crowded high end market. Will the sound appeal to everyone? Hell, no. If you need lean and crisp, look elsewhere. If you need an IEM that fits into small ears and doesn’t stick out like a combine harvester from each earhole, these aren’t ideal for you.

Will everyone get the best out of this IEM? Again, hell no. If you go universal, you need to put in the time and effort to keep rolling tips until you hit the audio jackpot and the sound expands around you like someone pressed zoom on your (audio) life. Going custom-fit will obviously alleviate this issue, but if Ambient can nail down exactly what tips make their IEMs sound the way they CAN sound when at their maximum potential (for me, the Flares Audiophile silicone) then they should buy the company that makes them and never include anything else in their universal tip loadouts again. The difference really is that ridiculous.

When you get the sound right, these IEMs will sound like nothing else you’ve ever heard before. Hyperbole or not, the is some of the most enjoyable and addictive sonic presentation I’ve heard since I got into this hobby, and not just from an “in ear”, but from headphones and speakers as well. The sheer solidity of the sound, and the richness of detail and nuance make this a very special sound. Price is obviously a barrier, but given the $4k+ IEMs now littering the market, this isn’t going to put too many TOTL-junkies off, I don’t think. As with all flagship models, you are paying a pretty chunky premium for a very small increase in sonic quality over the $500 or $1000 models on the market, but if you can afford it, the sound is something it will be very difficult to replicate (or better) elsewhere. Whatever Ambient were thinking when they started putting this mad science project together, I’m glad they did. Simply superb.

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