For the record, I was not sent these IEMs by 64 Audio, nor was I asked to write this review and have not been compensated for my time. I own three of the IEMs and was loaned the fourth. The views expressed here are entirely my own.
Before I start, I want to send a big shout out to @xenithon, my brother (literally, he’s my brother) but also my Sherpa for the past four years through this fascinating audiophile journey toward the summit. This review would not have been possible without you. Your wisdom, experience and kindness are not only a massive credit to this community, but mean everything to me personally.
I also want to extend my thanks to @twister6 and @mvvRAZ for their support and guidance in the lead-up to publishing this review – their mere presence on this forum elevates it to the very top of the hobby, and I strongly recommend anyone who wants to learn more about high-end portable audio takes note of what these guys are saying.
The full review is also available, with additional photography, on my blog.
Introduction
64 Audio needs no introduction, but here’s one anyway. The Vancouver, WA-based company, started by Vitaliy Belonozhko to make custom in-ear monitors for stage musicians, has grown to become one of the largest and most successful of the world’s high-end IEM brands.
Guided by Vitaliy’s engineering prowess, 64 Audio is known for pioneering unique technologies in its IEMs that challenge conventions and set them apart from other brands. These include:
• Apex (Air pressure exchange), the company’s in-ear pneumatic pressure relief system;
• LID (Linear Impedance Design), a way of correcting the non-linear impedance of an IEM’s drivers; and
• Tia (Tubeless In-Ear Audio), an open balanced armature design that sits in a tubeless acoustic chamber to maximise sonic performance.
For the first time ever (that I’m aware of), all four of 64 Audio’s high-end hybrid universal IEMs – Nio, Trió, Fourté and (Fourté) Noir – will be put through their paces and pitted against each other in a shootout of epic proportions. But unlike most shootouts, the goal is not so much to find out which is best, but instead discover what each IEM is best at.
Hopefully this will help anyone interested in these IEMs to choose which one (or more) might appeal to their preferences because, let’s face it – each one is like a supercar in its own right, and while some may be faster, more powerful or more aggressive, whatever your choice, you’re buying at the top end of town.
If you’re wondering why 64 Audio’s other two much-lauded universal IEMs, U12t and U18t, didn’t make the cut, it’s quite simple: they’re not hybrids. That doesn’t mean they aren’t as good or not as proficient as their hybrid siblings, far from it. Rather, I wanted to compare apples with apples, and in my opinion, all-BA designs offer a slightly different type of sound, with its own qualities, that almost makes them a different type of IEM altogether.
Because there’s so much ground to cover – this is essentially four major reviews in one – I’m going to dispense with the ‘small’ stuff, like packaging, accessories, the font used on the box, the tips they come with, the so-so stock cables, and so on, and jump straight into what you’re here to read about: the sound. l just want to briefly mention that I find 64 Audio’s earpiece design very ergonomic, and the shallower fit of the four hybrids – Fourté and Noir in particular – is among the most comfortable of all the IEMs I’ve used and owned.
That’s not to say the other stuff isn’t important when making your buying decisions, but there’s so much already written about it elsewhere (64audio.com is a great place to start, followed by the 64 Audio Head-Fi thread). Also, while I might reference techie stuff like frequency and tuning, I won’t explicitly be posting any graphs because again there are far better sources for these elsewhere (@crinacle'sIn-Ear Fidelity portal is the gold standard).
This review is ultimately all about how I hear these IEMs with my choice of music, and with luck, that’ll be of some value to you.
Introducing your contestants
Nio. The newest addition to 64 Audio’s high-end hybrid family, Nio was launched in mid-2020 and ranks as the highest driver count hybrid in the lineup, with eight BA drivers (including one Tia high driver) complementing its 9mm dynamic, for a total of nine drivers (hence Nio). Unlike the other three IEMs, Tia does not incorporate the full ‘Tia System’, as it eschews the tubeless acoustic chambers for a more traditional tubed design.
Nio is the only one of the four IEMs with swappable Apex modules, making it uniquely versatile in its ability to switch between tunings. In my opinion, Nio is also the flashiest looking of the bunch, with a striking blue abalone faceplate surrounded by a polished chrome rim and a glossy piano black paint finish.
Trió. Introduced in 2017 alongside the all-BA U12t, Trió (aka Tia Trió) is 64 Audio’s second Tia System IEM to feature a tubeless, single-bore design fronted by a nozzle-mounted Tia high treble driver (the first being the flagship Fourté). At the time, Trió was also the first IEM, along with the U12t, to feature LID technology that smoothed out the impedance response of its drivers, making the sound more consistent between the sources it was connected to.
With an internal M15 Apex module, Trió doesn’t isolate quite as much as the other hybrids (although Nio ships standard with the M15 module, it can also use the included M20 module for more isolation, and both Fourté flagships include a built-in M20 module). It’s also the blandest (or least blingy, depending on your taste) design, with a dark grey faceplate and a matte black body that’s rather understated considering its explosive sound.
Fourté. If memory serves, when 64 Audio announced their newest flagship in the latter half of 2016, it sent ripples through the luxury IEM market, not least because at $3,600 Fourté was one of the most expensive IEMs ever made, surpassing the price of most full-size flagship headphones at the time. While I want to focus this review on sound rather than cost, it’s worth mentioning if only for the heightened expectation the Fourté shouldered then.
Fourté was the pinnacle of what Vitaliy and his team had been working on for years prior – the Tia System. It was considered unorthodox if not revolutionary, with its distinctive burnt orange rim and genuine copper patina faceplate, and unquestionably remains one of the most unique, albeit polarising, high-end IEMs to this day.
Noir. Also known as Fourté Noir, 64 Audio’s limited edition, black-coloured, blue-accented flagship was more than just a different looking, different sounding Fourté. With only 500 units made, you could say Noir was a one-off design and shouldn’t really be part of the discussion (as it is no longer available for sale), but its appeal goes far beyond what its rarity suggests.
Noir features a re-tuned version of the original Fourté’s dynamic driver, larger venting chamber, all-silver internal solder, and a newer 8-wire stock cable (which, incidentally, wasn’t used in this review). The subtle but very audible change was made, as rumour has it, to better match Vitaliy’s sound preferences three years on from the launch of the Fourté, yet remains as polarising as the original despite its more approachable tuning.
Source: HiBy R8 DAP (low gain, Turbo on). Cable: PW Audio No. 10 8-wire 4.4mm. Tips: JVC Spiral Dot. Source files: lossless FLAC and DSD, local files only (no streaming). Apex modules: Nio was tested using the default M15 and mX modules only.
Bass
All four 64 Audio hybrids have outstanding bass quality. In my opinion dynamic drivers are best suited for producing an optimal bass response, creating more analogue sounding and more tactile bass than the faster but generally less dynamic (pun intended) BA drivers. Bass – especially sub bass – should be felt as well as heard, and that’s where dynamic drivers have an advantage over other driver designs. No matter how good a BA driver is at producing clean, textured bass, it can rarely deliver realistic rumble with lifelike decay and timbre.
Nio
Nio’s bass is really a story of two (M15 and mX) Apex modules (these are the ones I used for testing and the ones most people will likely switch between). With M15, Nio’s bass is a good few decibels louder than the other three IEMs, is well extended into the sub bass, but has more of a midbass emphasis. Nio’s bass has a rounder edge to it, so when drums hit they feel slightly cushioned. It has a good amount of texture and detail too, and a slower decay that gives it a very analogue feel. Talking relatively, Nio can sometimes be more bloom than boom, in light of the way the bass notes linger a little longer than perhaps they should.
Switch to the mX module, however, and the picture is flipped on its head. Now Nio has perceptibly (and measurably) less bass than all three IEMs, though that’s not to say its bass completely drops off a cliff. Sub bass is impacted the most, but is still present, as is midbass, and retains a good amount of texture and detail. All the bloom is gone, and while there can still be some rumble if it’s in the track, it’s fairly muted. Since bass levels are now lower relative to both midrange and treble, mX shifts the focus of the sound very much onto the mids (more on this below).
Trió
Trió has similarly elevated bass to Nio (M15), but is centred more on sub bass than midbass, which slopes down steadily to the lower midrange with no perceptible midbass bump. I hear Trió’s bass as more impactful than Nio, with a slightly more defined edge and more visceral punch. Rumble is deeper and more extended, while texture and detail are more or less on par, which is to say very good. Trió’s bass is also perceptibly faster, with a wicked dynamic slam that comes alive with both real and electronic drums, upping the energy compared to the more laid-back and softer Nio.
Fourté
Where both Nio and Trió have generously boosted low ends, Fourté is far more restrained in its bass bump. Closer to Trió in its sub bass emphasis, Fourté’s bass slopes down rapidly almost as soon as the rumble is done, to a fairly neutral level more in line with the midrange and below its elevated upper registers. Fourté’s bass serves as a foundation for the music rather than being the star of the show, but make no mistake, where there’s slam in the track, slam is what you’ll hear. Coupled with its internal acoustic chambers, Fourté’s bass tends to appear from nowhere and ‘fills the room’ with its presence. It’s also faster, cleaner, more detailed, more textured and better nuanced than Trió, giving real shape and dimension to drums and bass instruments and creating a better sense of space, though it may not have quite the same impact as its younger sibling.
Noir
Bass is one of the biggest tuning changes in Noir from the Fourté. Instead of sloping down from the sub bass, Noir’s bass remains fairly elevated through the lower midbass and then gently slopes downwards right though the upper bass and lower midrange until a sudden dip at 1kHz. This gives Noir a much warmer, thicker sound that, on the whole, maintains detail and texture but is not quite as nimble as Fourté. Despite its perceptibly thicker tone, Noir’s bass mostly avoids bleeding into the mids, but still presents with a slightly softer edge than the laser-like Fourté. Also, unlike Fourté, Noir’s bass doesn’t take a back seat in the mix, and is more reminiscent of both Nio and Trió with its bolder attack.
Mary Fahl’s Raging Child, the opening track from her rare 2001 EP, Lenses of Contact, delivers a powerful electronic drum medley at the 1:00 mark that is fairly well textured and quite resolving with Nio (M15) – picking up some distortion in the left channel at 1:10 that’s in the recording itself – but is also slightly bloomy and rounded. Switching modules to mX, the drums lose almost all the forcefulness, replaced by a more nuanced and textured rendition with the spotlight shifting to the vocals and supporting instruments.
Trió’s bass, by comparison, presents the same drums with a deeper tone, less midbass bloom and more subterranean sub bass rumble, while the drums appear from nowhere and ‘float in the air’ with Fourté, giving the sound a real sense of space, as if played back in a real room with real speakers, with exceptional texture and detail. Noir, on the other hand, is less like Fourté and more Trió (in depth) and Nio (in roundness). I could tell there was more sub bass energy here, but mixed in with a dollop of midbass that made the drums ever so slightly bloomy, and not quite as detailed and spatially defined as Fourté.
Ingrid Michaelson’s The Way I Am, from the 2006 LP Girls and Boys is an excellent test for bleed, and while none of the IEMs came close to bleeding over Ingrid’s silky vocals, Nio’s bloom and Noir’s thickness made the bass more dominant in the mix than was the case with Trió or Fourté, while Nio mX hardly registered any bass at all relative to the mids. Fourté was again the fastest and most detailed, followed closely by Trió and Noir, while Nio was slower, softer but still full of nuance.
Massive Attack’s Angel, from 1998’s Mezzanine is a litmus test for bass texture, quantity and thickness. The bassline that fades in from the start quickly establishes itself as the foundation for the track, and can tell you a lot about the bass response of an IEM. Nio M15 had the thickest presentation, with its elevated midbass, followed closely by Noir, with its similarly thick but more nuanced and less bloomy delivery. Both Trió and Fourté had less drone and more texture and rumble, their bass response leaning more to the sub bass than mid and upper bass. Coming in dead last was Nio mX, which effectively cancelled out the drone altogether.
James Blake’s Limit to Your Love, from his eponymous 2011 album, is a torture test for deep, strobe-like sub bass with midbass fullness thrown in for good measure (I always turn down the volume a few notches before playing this segment, which starts at 0:55 and repeats again later in the track). Interestingly the Noir gave the most visceral performance, its combination of sub bass depth and midbass fullness combining to highlight every warble of the eerie electronic effect. Nio M15 was likewise thick but less rumbly, while Trió and Fourté left little midbass meat on the bones while shaking the driver with sub bass, revealing the underlying texture a little better too. Nio mX tried but failed to move much air at all.
Midrange
Each of the four 64 Audio hybrids takes a slightly different approach to the midrange, either in driver configuration or tuning. Nio has the highest driver count of the lot, with six precision BA drivers for the mids and one BA driver for high-mids. Trió’s dynamic driver handles part of the midrange spectrum, along with a single precision midrange BA driver, while Fourté and Noir feature the unique Tia driver for the mids along with a single precision BA driver handling the mid-high handover. With so many different options you’d expect the midrange of all four IEMs to sound wildly different too, and while there are differences, they all share one important attribute: quality.
Nio
If I could only use one word to describe Nio’s mids, it would be lush. There’s a richness and wetness to the midrange, particularly with the M15 module, that makes female and male vocals sound both intimate and organic. With a gentle rise from 1kHz to 2kHz, the mids dip slightly before another small peak at 5kHz, bringing upper midrange vocals forward. This helps separate them from the elevated bass, though they retain the underlying warmth of the Nio’s bass blanket. While midrange detail and texture are decent, the finer technicalities are slightly subdued compared to the other hybrids, despite having the highest driver count of the lot. This can best be heard in instruments like piano, where key strikes aren’t as incisive as they are elsewhere, and guitar strings are also fuller and rounder, with softer transients.
It’s not that the Nio can’t be technical, because switching modules, Nio mX strips away much of the M15’s bass thickness and opens up the midrange, bringing it closer, technically, to the other hybrids. Vocals are pushed even more forward in this configuration, but not aggressively so, and clarity is dialed up a notch so that lyrics become more perceptible even at lower volumes. The tradeoff is some of the wetness of the M15 mids, and since highs are more dominant relative to the bass, the overall sound becomes brighter – yet far from what I would call bright. Instruments sound crisper, with more air between them, though not to the same degree as the Trió or Fourtes.
Trió
Trió’s midrange is slightly recessed, but only comparatively. Despite using a single midrange driver, Trió’s mids are audibly more detailed than Nio, likely a combination of the driver itself, the acoustic chamber, and some expert tuning. Trió’s mids also have fuller note weight, punctuated by two interesting dips at either end of the scale. Whereas both Nio and Trió dip at 1kHz, Trió’s dip is steeper, marking a sharper separation from the bass but also shaving some presence from the vocals. Where Nio pushes upper mids forward at 5kHz, Trió dips again. There’s a chasm from 5kHz until a sharp rise at 8kHz and again at 10kHz that could explain some of Trió’s brighter-leaning tendencies and occasional sibilance, and I wouldn’t be surprised if this is why I hear glassiness in some female vocals. Thankfully, as with all 64 Audio IEMs, these indiscretions are minor, and Trió benefits from 64 Audio’s tendency to tune in some transient roundness to guard against harshness.
Fourté
Fourté uses a dedicated Tia driver for its midrange, which must explain the clarity and speed of its transients. Compared to Trió, Fourté has slightly more energy and fullness in its lower mids, but comes across as more neutral and less dense due to the thinner bass presence. Its upper midrange dip is shallower and comes in sooner (4kHz) than Trió, rising up again at 5kHz to give upper mids more clarity than its sibling. Fourté’s superpower, however, is its unprecedented level of midrange detail, particularly microdetails. Every flick of tongue, parch in the throat, pluck of the strings and strike of the keys is presented with surgical precision, aptly supported by an even more detailed and upwardly-elevated Tia treble. Fourté’s mids straddle the line between too much detail and more relaxed musicality, but the sheer quality of its delivery puts it, to my ears, on the safe side of that line. It does, however, make the Fourté quite unforgiving of poorly recorded material, because you’re literally going to hear every imperfection, whether you like it or not.
Noir
One of the main changes to Noir’s tuning (its driver count and types being identical to Fourté’s) is in midrange presentation. Possibly because of an elevated midbass shelf and reduced energy in the upper mids, Noir’s mids are fuller and warmer than Fourté’s, reminiscent of Nio’s tuning but with much greater detail and less organic wetness. It also avoids Trió’s glassiness, filling out any hollowness in breathy female vocals with more detail and density. Like Fourté, Noir’s mids have an incredible amount of headroom, effortlessly delivering complex instrument passages and nuanced vocals, while maintaining the same palpability and realism in more sparse compositions. Where it differs from Fourté is precision – the air between instruments not quite as black, the placement of instruments and vocals slightly less distinct, but in return it gains some musicality where Fourté leans more towards dryness and neutrality.
Katie Pruitt’s It’s Always Been You, from her phenomenal 2020 debut album Expectations, is a perfect example of raw emotion mixed with both lower and sweeter vocal overtones. As the song hits its crescendo around the 4-minute mark, Nio’s (M15) rich and organic midrange comes to the fore, sacrificing the last word in detail for a fair amount of warmth, with a sweetness to the softer notes belying the passion in the lyrics. Nio (mX) is drier and lighter in tone, revealing more detail in the vocal inflections. Trió takes the detail of Nio mX and turns it up a notch, along with a hint of warmth, albeit not quite as warm as Nio M15. Fourté dials down the warmth, replacing it with even more detail, texture, air and nuance than Trió. It’s easily the most lifelike delivery, but can come across as slightly dry when compared to Nio and Trió. Noir, on the other hand, is fuller than Fourté while maintaining a similar level of detail and texture, with a hint of wetness and slightly less air. It’s also slightly more forward than Fourté and Trió, but not quite as full as Nio M15.
Neil Diamond’s Hello Again, from the 1980 soundtrack to the movie The Jazz Singer, showcases Nio’s (mX) dexterity with baritone male vocals, delivering a smooth rendition of Diamond’s heartfelt vocals interspersed with well-defined piano and strings. Switching to M15 brings more wetness to the vocals, but also more bloom and weight added by the extra bass presence which makes the vocals more organic sounding. Piano and strings also sound fuller, with a more lifelike decay compared to the drier mX, but sacrificing some microdetail in the process. There’s noticeably more detail in the piano keys, strings and texture of the vocals with Trió. Though not as warm or organic as Nio M15, Trió’s midrange is not too dry here either. By contrast, Diamond’s voice loses some of its chestiness with Fourté, his delivery becoming airier, while strings and piano are played with a lighter touch and better definition than Trió. It’s also easier to pick out shuffles and other microdetails in the recording with Fourté. Noir ups the warmth, much like Nio M15, and is fuller than both Trió and Fourté. Vocals have a similar weighty bloom to Nio, being more chesty but less airy and nuanced than Fourté, though arguably more lifelike too. Piano and strings are not as clearly defined as Fourté, falling more in line with the vocals.
Holly Throsby’s What Do You Say? (featuring Mark Kozelek), from her 2017 album After A Time, is a harmonious interplay of sweet female and resonant male vocals along with well-recorded guitars and percussion effects. Two different guitars introduce the song, one in each channel, played with warmth and clarity with Nio (M15). Holly’s soft, sultry and sweet vocals have a deft touch, sounding almost ethereal in contrast to Mark’s deeper, more resonant vocals as they interplay in the chorus at the 0:40 mark. With the mX module, the intro guitars aren’t nearly as warm, and Holly’s voice is slightly drier too, but more detailed as a result. Mark’s vocals aren’t as warm either, with more edge to them. Trió injects energy and verve into the guitar intro, but also some glassiness into Holly’s vocals. She also sounds more forward in the mix, with Mark set further back, likely the result of Trió’s lower midrange dip. Fourté adds realism and air between instruments and vocals. Holly is no longer glassy, back to her sweet and sultry self, with even more nuance, and while she’s still quite forward in the mix, Mark isn’t set as far back as with Trió, his voice coming across as more airy and less chesty. Noir adds warmth into the mix, Holly sounding fuller, and Mark sounding closer, adding some real intimacy to the vocal presentation.
Miriam Stockley’s Fantasy – Sicut Cervus, from her 2006 LP Eternal, is all about vocal and instrumental harmony. Almost operatic in its delivery, Miriam’s mesmerizing voice stretches Nio’s midrange capabilities to the limit. With M15, there is an underlying bloom that almost, but doesn’t quite detract from Miriam’s chanting but does blend in with the choral cues that float around the stage. With mX, those cues become more present in the mix, but still remain well separated from the main vocal, blending in more effectively. Miriam’s voice also seems clearer and less ethereal, which actually benefits the song. Trió’s presentation is fuller than Nio mX but less bloomy than Nio M15. It’s also a fair bit more detailed. What I heard as slight distortion in the upper right channel with Nio is actually a woodwind instrument of sorts, which Trió renders more distinctly. The trailing edges of Miriam’s voice are also sweeter here. Fourté lays bare all the subtle nuances of Miriam’s voice. Without any bloom, the choral blend of male and female voices fills a larger space compared to Trió, and I can almost picture the performance taking place in an ancient stone cathedral. Noir sees the return of an ethereal air to the vocals, with more reverberation around the room. The delivery is warmer than Fourté, with some of the subtle cues less clear through the warmth, but is still more airy than Trió and more detailed than Nio.
Treble
The first thing that comes to mind when you see the word Tia in the context of 64 Audio IEMs is treble. Other than Fourté (and the out-of-production Noir), all current 64 Audio IEMs that feature a Tia driver use it solely for treble (whereas Fourté and Noir use a second Tia driver for midrange). And while the concept of an open BA driver is not unique to 64 Audio – Unique Melody created a type of open BA driver prior to Tia – the way it’s been implemented by 64 Audio makes for a very special treble experience indeed. All four hybrids have excellent treble resolution and extension, but each has been tuned very differently, as we’ll see below.
Nio
When you’re aiming for easy listening, you can’t have too much treble in the mix, and that’s exactly how Nio rolls. Without necessarily chopping off the highs, Nio’s M15 treble slopes down steadily from 6kHz, occasionally lifting back for some energy before one last ‘peak’ around 17kHz adds a breath of air to proceedings. Switching to mX doesn’t change this tuning much, but because the bass is significantly reduced, what treble energy there is becomes more apparent. Compared to the other three hybrids, Nio has a relaxed but still well extended treble, and its Tia DNA means it doesn’t come across as overly dark either.
Trió
Trió unleashes the full force of its Tia treble driver and takes no prisoners in the process. Its treble elevation, which includes lofty peaks at 8kHz (climbing steeply from 6kHz) and another at 10kHz, give the Trió an edgy bite and ‘zing’ that can, on occasion, cross the line between smooth and harsh, and inject some wayward glassiness and the occasional sibilance in female vocals – especially in poor recordings. It also gives Trió its tremendous energy and clarity, extracting maximum detail and creating a vast, almost holographic stage in the process. Thankfully, the majority of Trió’s treble indiscretions are tempered by its subwoofer-like bass, giving Trió a fun V-shaped tuning that literally screams quality.
Fourté
Fourté’s overall tuning has been the source of much debate in the audiophile community for many years, but if there’s one thing everyone can agree on, it’s the treble. Fourté’s treble is unashamedly huge. It boldly rises above most other frequencies, cresting in a K2-like peak at 8kHz that overshadows Trió and extends far beyond the horizon to give the music a grand and airy scale quite unlike any other IEM. Normally this type of tuning – and this much treble – would render an IEM overly bright or harsh, but Fourté somehow manages to avoid both. Yes, it leans toward bright, but the treble is so well controlled, with so much detail and finesse, that it actually comes across as smooth and lifelike on most occasions. Granted, when playing poor recordings or music that’s been purposefully mastered brighter, Fourté can be unforgiving, so lovers of high-energy, bass-light, bright and edgy music should use Fourté with caution. But give it well-recorded, well-mastered material and you’ll be treated to treble that’s still considered the gold standard by many enthusiasts today.
Noir
For anyone who thinks Fourté’s OTT treble can sometimes be too much of a good thing (or just too much), Noir is an interesting alternative. Its treble tuning has been tamed slightly compared to Fourté, with a smaller 8kHz peak that brings the treble in line with the upper mids and bass, allowing the other frequencies to play a much bigger role in the music. The contrast between the Noir’s thicker bass, warmer mids and the still elevated treble is such that when there is a hint of glare in a track, or a bright splash of sound in the middle of a darker recording, it seems to stand out more with Noir. That said, Noir’s superb treble technicalities still elevate it above most other IEMs, and while it’s not quite as airy or ethereal as its twin, it stands head and shoulders above Nio and Trió when it comes to sheer quality.
Def Leppard’s Love Bites, off the 2017 Remastered 30th Anniversary Edition of the classic album Hysteria, is a litmus test for a brighter recording with high-pitched vocals and multiple crashing cymbals. Nio (M15), with its relaxed treble, gives the chorus [1:50 – 2:12] a cushion of warmth, letting the cymbals wash over your ears like warm spring water, with about as much edginess as you’d expect from warm water washing over your ears. The thickish bassline keeps the brighter notes from going wild, making for a more relaxed version of this ultimately mellow power ballad. Even with mX, Nio doesn’t go OTT with the brightness of this track, the treble having just enough sparkle to be interesting, but not too much that it becomes strident. Trió’s potent bass drums dominate the cymbals so they’re not overly splashy, but it’s the screaming vocals the stand out with greater detail and more energy than either Nio configuration. While I wouldn’t necessarily call Trió bright, I wouldn’t want to turn the volume up too much on this track regardless. Fourté tips the balance in the opposite direction, making the crashing cymbals front and centre and relegating the bass drums to the background. The vocals are also more exposed, but come across smoother than Trió, albeit dominated by the cymbals. If ever you want an example of Fourté’s treble-first approach, this is it, and when combined with imperfect recordings like this one, the brightness can sometimes get too much. This passage illustrates the different approach 64 Audio took with Noir’s overall tuning compared to Fourté. Back come the drums to balance out the cymbals, which, while still bright and detailed, aren’t nearly as forward as they are with Fourté. It also gives the vocals more room to breathe, and while Trió is still fuller and warmer, and Nio even more so, Noir brings just the right mix of energy and clarity, making it the pick of the bunch for me.
Missy Higgins’ Shark Fin Blues, from her 2014 covers album Oz, is my go-to sibilance test for female vocals. With her strong Aussie twang and slightly wispy voice singing the opening lines: “Standing on the deck watching my shadow stretch / The sun pours the shadow upon the deck”, if there’s any sibilance to be heard from an IEM, you’ll hear it. The Nio (M15) has no such problems. The vocals are effortlessly smooth, with a warm and inviting softness that lets you sit back and take in the words without a hint of fatigue. There’s no bass or drums to round off the sibilants either, but switching to mX still doesn’t make the vocals any more “essy” than they can be. Instead, mX renders them with more clarity and a hint more ‘grain’, though not in a bad way. To my surprise, Trió doesn’t show any signs of sibilance on this track either. In fact, I found it slightly less edgy than Nio mX, helped perhaps by the quality of the recording. Further into the track there is a bit more woosh in the vocals, but the added fullness makes Trió’s version a very solid and engaging listen. Fourté is where I thought things might go south, but again to my surprise they did not. Instead, Missy’s voice becomes more airy, almost ethereal, floating across the sharper piano strikes. When she sings “I see the sharks in the water like slicks of ink / Well, there’s one there bigger than a submarine”, there’s a sense that things might be hotting up, and yet she stays on the right side of the sibilance line for me. What I didn’t expect was for Noir to get closer to the line than Fourté (or Trió for that matter), and yet the contrast between the warmer, fuller piano strikes and decay, and the still forward treble of Missy’s trailing consonants, makes them stand out more than they otherwise would.
Angels of Venice’s Trotto, from their self-titled 1999 album, features a colourful combination of unusual mediaeval instruments played with a sparse yet mesmerising rhythm. Large leather drums are offset by a lively whistling flute in the right channel from 1:27 and again (with an even higher pitch) from 3:27, while a stringed instrument evokes both lower and upper treble from 2:27 onwards. All three passages showcase Nio’s (both mX and M15) relaxed treble tuning, but retain a good level of sparkle. The main difference between the two is M15’s heightened warmth and fullness in the drums, which adds more contrast to the treble given the instruments are played relatively far apart from each other in the track. Trió adds more contrast to the mix, the drums becoming larger and more full-bodied, and the whistle and strings (and occasional stick hits on some sort of metal surface) resonating with greater detail. And then there’s Fourté. For all the talk of hot treble, Fourté takes the crispness of the whistle, the texture of the strings, and sharp trailing edge of stick hits and spreads them across a holographic stage, using the faintest of cues to create a vivid, layered soundscape all around the head. Fourté’s world-class detail retrieval is exemplified here, as is its sheer transient speed that effortlessly reveals the physical properties of each instrument. With Noir, the drums return to their Nio and Trió fullness, echoing all over the stage, which overpowers some of the finer details in the whistles and strings. When the track gets really busy around the 3:04 mark, drums going, strings screaming, Noir’s presents a wall of sound interspersed with sparkling highlights, belying a very different tuning to Fourté’s more intricate and layered rendition.
Max Richter’s Winter 1, from his 2012 album Recomposed by Max Richter: Vivaldi, The Four Seasons, is a great example of speed, detail and treble timbre, especially in the violin salvo from 1:15 onward. Nio (M15) makes the strings sound a touch hollow, and not particularly fast either, likely a result of its more relaxed treble tuning and (comparatively) less resolution in this region. Switching to mX, things improve considerably, the strings becoming more rounded and tactile, and also a little faster. Something in the balance between bass, mids and treble prevents this passage from sounding ‘correct’ with the M15, but Nio’s versatility with a module switch means it can better handle a broader range of genres. Trió splits the difference, infusing the strings with more detail and speed than Nio M15 but less finesse than Nio mX to my ears. It’s a touch more strident than I’d like, but still very agreeable. Fourté switches gears and adds layering and complexity to the strings that’s simply not there with Nio or Trió. No longer a contiguous group of violins, I can clearly hear different sections of the strings playing at different speeds in the left (faster) and right (slightly slower) channel, and with the bass more in line with the violins, Fourté creates a sense of depth and space with more air around each instrument and the orchestra as a whole. Noir doesn’t deviate too far from Fourté’s presentation on this track, the strings sounding slightly fuller but with enough detail to differentiate between the groups of violins in each channel. The space around the orchestra is slightly smaller though, the air around the instruments not as black, with a hint of warmth that slows the pace just a little compared to Fourté but makes the whole more cohesive in the process.
While I wouldn’t call any of 64 Audio’s hybrids neutral, I would say they all strive for a fairly balanced tonality. Yes, each IEM has its own splash (or two) of colour, but there’s no wild colouration going on that pushes any of them into a corner. There’s an undercurrent of warmth that makes listening to all four IEMs very pleasant, which is more evident in some (Nio) than others (Fourté). There’s also a natural smoothness to the sound that softens some of the harsher edges, but again this varies quite markedly. Overall, I’d say all four IEMs have been, to my ears anyway, very tastefully and deliberately tuned, even though some of the choices 64 Audio made won’t be to everyone’s taste.
Nio
Nio is tuned with a mild L-shaped signature or more of a W, depending on which Apex module you’re using. I’d call the M15 more of the latter, with its midbass-centred elevation (which is well above neutral, mind you), giving the overall tonality a warmer, darker, more organic appeal than the lighter, nimbler mX. With mX, the signature is more of a W, but a gentle one given that neither bass nor treble are dominant.
That said, in both configurations, Nio is still more natural than analytical; in fact, you can argue that Nio doesn’t lend itself to analytical listening at all. The added thickness of the bass with M15 is only really problematic with music that is already bass-thick, and any hint of veil is only there when compared to the other hybrids with their even more neutral, drier midrange. Nio’s is a safe tuning in that there are no sudden peaks or dips to make the music sound wonky or uneven, making for a very relaxed, easy listen.
Trió
With a mild-ish V-shaped tuning, Trió is all about energy and detail in equal measure. Trió displays resplendent control in every department, from a bass that’s bold but clearly delineated from the mids, to a midrange that openly flirts with neutrality while retaining a hint of warmth to keep things interesting, and a treble that cares not for restraint yet somehow mostly stays on the safe side of piercing.
That’s not to say Trió’s tuning is without issues. For example, there’s something going on with Trió’s lift in the lower treble following a sharp upper-midrange dip that adds a glassiness to the trailing edge of some female vocals, and the impressive treble energy can be a bit too zingy at times. These anomalies are rare, though, usually only showing up in brighter or poor recordings, and overall Trió’s is a mature tuning, making for an exciting, dynamic listen.
Fourté
Either skewed W or bright-leaning U is how I’ve heard the Fourté’s tonality described in the various reviews I’ve read, but to my ears it’s more former than latter. While its treble elevation and energy is definitely the dominant factor, this doesn’t overpower the bass or the mids on well-recorded, well-mastered tracks. Fourté’s is not a neutral tuning by any measure, nor is it strictly ‘reference’, with some dryness in the mids and a hint of warmth and smoothness that makes it effortlessly listenable for long sessions.
Fourté’s tuning challenges convention. Its sound doesn’t come at you from predictable angles, but instead jumps out from odd angles that could take some getting used to at first, especially with familiar music. It’s not a linear tuning like Nio or Trió; rather, it keeps you guessing, filling the virtual space with sound that appears out of nowhere. Vocals can be intimate or distant, depending on the track, and sometimes both on the same recording. This unpredictability has lead to some people calling Fourté’s tuning wonky, but to me it’s delightfully quirky, making for a big, airy but ultimately highly refined listen.
Noir
Describing Noir’s tonality as a fuller, warmer Fourté does great disservice to its tuning. While it shares many of the technical traits of its twin, Noir reigns in Fourté’s occasional brashness, adding a richness from its midbass, some wetness in the mids, and dropping the temperature on its treble to create more cohesiveness and very different tonal balance.
Noir’s superpower is its ability to maintain world-class clarity despite its warmth, which – considering how closely it graphs to the Fourté – must be down to more than just tuning alone. Bass is big, and occasionally bloomy, but that bloom never suffocates the other frequencies to the point where clarity is negatively impacted. Treble is likewise elevated, but also smooth, and mids are raised enough to excite without becoming shouty.
Noir’s sound is for sure denser than Fourté’s, but it’s all muscle no flab, and ultimately presents a very engaging listen.
Heidi Talbot’s If You Stay, from her 2008 album In Love + Light, opens up with a delicate interplay between two acoustic guitars, overlaid by Heidi’s wispy vocals. Nio’s warm, inviting, organic M15 tonality makes it sound like liquid honey. With mX, the guitars have substantially less tonal weight and Heidi’s vocals are less syrupy too, but the overall tonality is still warm enough to evoke images of a fireplace on a cold winter’s day. Trió tones down the warmth quite substantially in the vocals, but the low notes on the guitar still resonate with a warmer, thicker decay, even more so than Nio. There’s more of an edge to the vocals too, belying Trió’s slightly dry voicing with upper register female vocals, and the strings have more bite to them as well. In contrast to Trió’s fuller tonality, Fourté is clearer but also smoother. Heidi’s vocals are more forward, breathier, and the strings have a lighter, airier touch to them. Noir’s inherent warmth is complemented by its exceptional clarity. Vocals are pushed a touch more forward than Fourté which, combined with a forward treble, does make them a hint splashier, but the musicality is off-the-charts good with this track.
Boston’s More than A Feeling, off their eponymous 1976 debut, is a brighter recording that greatly benefits from Nio’s warmer M15 tonality. Drums have great weight to them, and the guitars, while not quite as energetic sounding as I’ve heard them with faster IEMs, still have plenty of crunch. Nio mX lacks that extra weight and bite, and its tonality is flatter with this track. Vocals are pushed more forward, with the instruments playing a supporting role. Despite a leaner touch, mX maintains Nio’s inherently warm smoothness, but perhaps a touch too sedately in this case. Trió restores Nio’s M15 weight, bringing both drums and guitars to the fore while pushing the vocals back. It’s a fuller tonality too, but more nuanced and detailed, with just enough bite to satisfy and significantly more energy too. I wasn’t sure quite what I’d get with Fourté’s brighter tonality, and while it’s indeed brighter than Trió and Nio, it’s also smoother, more balanced and more revealing. Vocals are also more lifelike, and the guitars, drums and vocals don’t compete for space but instead are perfectly balanced in the mix. Noir maintains that balance, but injects it with its trademark warmth. Vocals are wetter, drums are fuller, guitars maintain their edge, but there’s also more contrast between the warmth and the occasionally sharp treble bump that makes trailing vocal edges and guitar riffs stand out more than they do with Fourté.
Dire Straits’ Brothers In Arms, the title track from their 1995 album (2015 20th Anniversary DSD remaster), mixes synth effects, a low, rumbling bassline and Mark Knopfler’s iconic guitar and vocals to create a delicately rhythmic and ultimately very dynamic track. Nio does a commendable job with its inherently relaxed tonality, adding just the right amount of weight with M15 and resolving the softer vocals better with mX. Trió offers up more contrast between the smooth vocals, poignant guitar and drumstick hits, its deeper low end neatly balancing out the brighter parts of the track. The rumbling thunder in the intro fills up Fourté’s massive stage, creating an enormous sense of space for the song. Stick hits echo into the distance, the vocals perfectly centred, guitars blending in with the synths and other effects, matching the ebb and flow of the track as the story unfolds. Noir’s stage isn’t quite as large, but its pacing is superb, adding a softer rumble like Nio, with fuller, warmer vocals than Fourté giving the track more intimacy.
Sarah McLachlan’s Angel, from her 1997 album Surfacing, has to be one of my all-time favourite tracks, creating a very deep emotional connection almost as soon as I hear the opening piano chords and Sarah’s otherworldly voice. Nio’s M15 tonality gently cushions each key strike, and gives the lower registers a warm, weighty resonance. Sarah’s voice comes across as ethereal, with a dream-like glow that makes me close my eyes and allow the music to quietly flow over me. The same Nio softness is still there with mX, though not quite as dream-like. With Trió, the edges of the piano keys are better defined, with excellent balance and weight, but Sarah’s voice loses some of that captivating Nio fullness, becoming drier, and is set slightly back on the stage. There’s also a bit of glassiness in her breathing that wasn’t there with Nio. Fourté’s tonality is dead-on perfect with well-recorded piano tracks, and this is no exception. Every strike is rendered with great detail, and just the right amount of sustain to sound utterly lifelike. Sarah’s voice, while not quite as dreamy as it is with Nio, sheds all of Trió’s glassiness and is also set more forward. It’s an airier, lighter voicing, but also very believable, with a subtlety that belies the emotion in her words. Noir’s thicker tonality translates into more weight in the piano strikes, but without any of the bloom or softness of Nio or the elevated heft of Trió. Sarah’s voice is fuller too, but also warmer, with a slight wetness that makes it more palpable and intimate.
Soundstage, separation and imaging
The mark of 64 Audio’s designs is the combination of a refined, mature tonality with outstanding technical ability. Nowhere is this more apparent than in the four hybrids’ ability to cast a generous stage, across which instruments are spread and then precisely played back so you can almost see them in the virtual space. The degree to which each IEM achieves this effect varies, influenced in part by tonality, but more so by the very specific design and placement of the drivers – particularly in the three tubeless Tia System IEMs.
Nio
For a relatively warm and sometimes dark-leaning IEM, Nio (M15) casts a fairly wide stage, with good instrument separation and generally credible imaging. On bassy tracks the space between instruments can get a touch wooly, but retains a sense of balance, and instruments generally don’t overlap unless they’re recorded that way. mX opens up Nio’s soundstage, with similar width but more perceptible depth. Instruments also have more air between them, which is cleaner too, and their position is easier to pin down. Panning effects are also more obvious.
Trió
Trió casts a wider stage than Nio (in either configuration), and has a better sense of layering, separation and imaging. Some have called Trió’s stage holographic, but with the exception of a few tracks that have been recorded in a way, I hear Trió as wider rather than deeper, and there’s not too much by way of stage height either. This is purely by comparison, because Trió is indeed very spacious, with superb separation and imaging capabilities.
Fourté
If there’s an IEM that creates a larger soundstage than Fourté, I’m yet to hear it. Not only can Fourté – with the right material – stretch the physical boundaries of the stage well beyond the width of my head, it also spreads it outwards, upwards and downward to create what can genuinely be described as holographic space. At the same time, Fourté separates every instrument, vocal and sound effect with such precision, that you’ll be hearing layers upon layers of audio cues in familiar tracks you never knew existed. Add to that a sense of pinpoint instrument placement in the 3D space – imaging that doesn’t only place but also tracks the movement of sound across the stage – and you have the very best stage, separation and imaging reproduction I’ve heard in any headphone format, including my previous benchmark, the HD800.
Noir
Noir trades the endless expanse and precision of Fourté’s stage, separation and imaging for a warmer, more intimate, more cohesive presentation. That’s not to say any of these are short of excellent. Noir’s stage is smaller, yes, but not by much – probably closer to Trió than Fourté – and more oval shaped instead of infinity cubed. Where Fourté paints pitch black darkness between instruments, Noir heats the air up a little, giving it some padding in the same way Nio does with its warmer tilt, but in return this makes the space more natural and organic than Fourté’s surgical theatre. Imaging doesn’t suffer quite as much as Nio though, with instruments placed precisely in the space, and panning effects are just as sublime as they are on Fourté.
Lily Kershaw’s Always And Forever, from her outstanding 2019 album Arcadia, mixes electronic beats with layered effects and oversampled vocals to create a wide, deep soundscape, anchored by Lily’s pristine voice. At 2:50 there’s vocals split to the left, joined by another at 2:56 to the right, then all three harmonise together, the left and right repeating the lyrics ‘I feel holy’ while Lily continues singing. Nio faithfully recreates the stage (with both mX and M15) modules, giving each element room to breathe, and clearly maintains the three vocal layers in their own space. Trió pushes the left and right channel vocals slightly further apart, creating a wider stage with more space between the various elements of the track. Fourté doesn’t push the vocals further apart, but instead sets them slightly back in the stage, creating a better sense of depth. Noir maintains the Fourté’s sense of depth, but on a slightly smaller stage, pushing the vocals closer to centre but still distinctly separate.
Al Di Meola’s Traces Of A Tear, from the 1985 LP Cielo E Terra presents a vast open space with sparse, intricate and interesting instrumental cues, often appearing unexpectedly in different parts of the stage, and occasionally panning right-to-left and left-to-right across the stage. Nio’s M15 stage is fairly wide here, the instruments comfortably occupying their own space. At 0:50 a shaker rattles from the far right and quickly pans across the stage to the left, then back again. The panning is very accurate with both mX and M15, but the location of the various instruments, while clear, is slightly less accurate than it is with the other three IEMs. Trió’s stage is again wider, and also deeper than Nio, the instruments precisely placed, and the panning effects are equally precise. Fourté’s stage is wider still, the layering of sounds more intricate and nuanced. The shaker seems to come at you from 3D space, moving closer to your eyes from the right and away from your face as it pans left. If ever you need a track to demonstrate Fourté’s holographic stage, use this one. With only the guitar strings adding warmth to the sound, Noir’s stage is vast, wide and deep here, the panning effects as realistically three-dimensional as they are with Fourté. There’s a touch more overlap between the instrument echoes, melding them together into a more cohesive whole.
Pink Floyd’s Time, from their iconic 1973 album Dark Side of the Moon starts off with a famous clock intro that…well, you know, and if you don’t, go listen. It’s an overused showcase track for imaging, separation, clarity and detail, but since it’s also one of my all-time favourite songs, I’m happy to include it here. Nio (M15) does a decent job of placing each clock in its own space, but doesn’t have the depth of space to layer them so that they don’t overlap too much, blurring some of the edges. With mX, Nio does a marginally better job, but some of the fundamental ‘gears’ of the clocks (that I know are there) are missing. Trió’s stage is notably wider here, deeper and more detailed too, with the clocks spread out on more of a 3D-axis than in overlapping rows like Nio. Almost all the fundamentals are audible, but be careful that Trió’s zing doesn’t take an eye out with some of the clock chimes in the right channel. I was almost afraid to try Fourté with a room full of brightly-chiming clocks, but as it turns out, its left me with only partial hearing loss in my right ear. Seriously though, Fourté lets you hear every chime, ding, scrape and gear rattle in real-time, creating a marvelous kaleidoscope of excited clocks you can almost touch. Noir’s warmer sound takes some of the metallic energy out of the clock strikes compared to Fourté, which is a good thing really because the smaller stage brings the clocks a little inward, closer to your head. You can still hear them all just as well as you can with Fourté.
Meiko’s (Sittin’ On) the Dock Of The Bay, off her 2018 covers album Playing Favorites, is a binaural recording by David Chesky that places instruments around a fairly large room, with Meiko closest to a ‘dummy head’ microphone in the middle. An IEM with good imaging should give you a sense of where each instrument is in the space, and also track Meiko as she moves around the microphone. It’s only Meiko and her guitar until 1:25, when a drum and tambourine start up in the left channel, and what sounds like a bass instrument of sorts in the right. Nio (M15) does a credible job, to a point. Though the drum and tambourine seem fairly close to the singer, the exact placement of the bass isn’t entirely clear. mX adds some air between the instruments, but not much, helping to focus the imaging slightly. Trió steps up both imaging and separation considerably. The tambourine, which sounded like it was being played by the drummer, is actually set off to the left of the drums, which are in turn set further back in the room, and the bass on the right is closer to Meiko, Trió’s powerful low end casting echoes off the walls that better define the dimensions of the space. Fourté adds height and even greater depth to the stage, placing the drums further back, the tambourine forward and further left, and pinpoints the location of the upright bass instrument on the right. It’s Noir, however, with its thicker and more resonant bass combined with excellent imaging, that creates both a sense of space and size, Meiko’s warmer and more intimate vocals making Noir the ideal pairing for this track.
Speed and dynamics
Hybrids can suffer from incoherency between their slower, more analogue dynamic drivers and faster, more precise BA drivers. To my ears 64 Audio’s hybrids don’t have too many coherency issues, although the contrast between the slower, rounder bass notes and decay on Nio (and Noir) is occasionally apparent. The reason I mention this here is that it affects how I hear the overall speed of the four IEMs. All four are generally very fast and dynamic, however, with a deftness of touch when it comes to scaling from the softest to the loudest parts of the music.
Nio
Without contradicting what I’ve just said, let me qualify it by adding that of the four IEMs, Nio is the slowest. A better term would be relaxed, because technically speaking Nio isn’t slow. But its big, bold and sometimes bloomy dynamic bass with M15 pulls on the reigns, as does its more relaxed treble tuning. With a Tia driver doing treble duty the music’s upper fundamentals are never going to be left too far behind, and switching to mX the bass cleans up nicely, showing that Nio is capable of a quicker dynamic attack and decay when it’s called for.
Trió
Whereas Nio is politely reserved, Trió is unapologetically fast and dynamic. Yes, it has a big dynamic driver that doesn’t always keep up with the super-fast BA in the mids and even faster Tia treble driver, but since bass is centred more on sub bass than midbass, it doesn’t hold back the other frequencies much at all. There’s a real energy to Trió’s dynamism too, constantly fed by a sometimes over-exuberant treble and complemented nicely by its large-yet-nimble and very punchy bass. Trió can softly ping just as hard as it slams, so best prepare your ears for the rush, especially if dynamically aggressive music is your thing.
Fourté
Speed is what Fourté is all about. Never mind the fact that it has a dynamic driver, the agility of its bass blends in almost seamlessly with the nimbleness of its midrange and treble drivers. It might not be technically as tight as an all-BA IEM like the U12t or U18t, but it compensates with authority and a lifelike analogue decay that’s physically impossible for BA woofers to fully replicate. It’s also incredibly dynamic, rapidly delivering high/low volume switches, but doesn’t quite match the dynamic thwack of Trió’s potent bass slam.
Noir
Compared to Fourté, Noir slows down the pace somewhat without making it too apparent. Its thicker, bolder low end emphasizes decay over swiftness, and while excellently textured, the bass doesn’t match the tightness of a BA woofer (or indeed Fourté’s dynamic). Still, Noir manages to match Trió note for note when it comes to speed, even though its notes are thicker, but when it comes to overall speed, Noir’s dual Tia drivers are akin to mini afterburners. Dynamics don’t take much of a hit from the added warmth either, but I don’t hear the Noir as any more dynamic or energetic than Trió. If anything, the latter has more zing, while the Noir is more refined.
Rush’s Vital Signs, off the band’s 1981 LP Moving Pictures (West Germany 1st Press Edition), is a progressive rock classic that features some incredibly dexterous work by drumming legend Neil Peart. The snare drum hits accelerate as the song nears its crescendo at 3:50, and the mix of drums, synths and riffing require perfect timing to come off just right. Given the slightly dry nature of this particular recording, Nio (in both configurations) injects some much-needed warmth to the sound, but also admirably manages to keep up with the pace. Trió does too, but at a canter. The snares also hit harder and the drums sound punchier than Nio’s, adding weight to go with the speed. Fourté tells it like it is: fast, dry, musical, rhythmic. Every snare stroke, stick hit, orchestral string (in the background) and accompanying vocals are played in perfect balance, with great precision. It almost turns what’s already a great recording on Nio and Trió into a live session. Noir is likewise pacy, but the layering isn’t as clearly defined as it is with Fourté. The drums and snares are melded in with the rest of the instruments, though nothing gets muddled in the process either.
Dadawa’s Sister Drum, the title track from her 1995 album, is an incredibly dynamic track that features a slow, soft buildup and recurring bassline, with Dadawa almost whispering her words before a massive Chinese drum salvo reverberates around the cavernous space. Nio’s (M15) big bass driver is custom-made for this track, giving a good account of the scale of the drums while rendering the quieter parts with a fair amount of detail (not that I understand the words to know how clearly I’m hearing them). Nio mX, on the other hand, is not a good fit for this track. The drum hits are more like soft slaps, losing impact and texture in the process, and while the quieter passages are rendered clearly, that’s only half the song. Trió bring things back to where they should be, evoking even more nuance from the quieter passages, and adding punch and slam to the drums. The stage is also wider, giving the sound more room to breathe. Fourté’s comparatively restrained bass still has more impact than Nio mX, but not quite as much as Nio M15 or Trió. It makes up for it with incredibly tight, textured bass, while making even the faintest whisper in the build-up clear as day. Noir is the perfect storm of Trió’s impact and Fourté’s detail. It’s not quite as punchy as Trió, but its defter in touch, and still very dynamic.
Nils Lofgren’s Keith Don’t Go (Ode To The Glimmer Twin), from his 1997 Acoustic Live album, features a mesmerizingly-fast guitar riff from 4:08 that really tests an IEMs upper midrange and treble speed. As expected, all four 64 Audio IEMs ace this test, their Tia drivers easily keeping pace with the music. Even Nio, with its more relaxed outlook on life, follows Lofgren’s plucking with aplomb. Naturally all three Tia System IEMs – Trió, Fourté and Noir – cruise through this passage, though tonally they’re quite different. Trió’s version is rather zingy, with something about its tuning resulting in an overly sharp rendition. Fourté’s is surprisingly fuller and more detailed, the reverberations of individual strings seemingly radiating off the guitar body in a gobsmacking display of resolving power. Noir is closer to Fourté than Trió, with a bit more body in the lower notes that resonate from the wood.
Armin van Buuren’s Intense (featuring Miri Ben-Ari), the title track of his 2013 LP, features an intricate interplay between his array of electronic effects and Miri’s violin, with a deep drop and bold beat that picks up the rhythm as the track gathers pace. Nio M15 keeps the pace but doesn’t quite capture the full dynamic range of the interplay, coming off as slightly restrained. Switching to mX does little to help Nio’s pacing, dropping the bass weight without really picking up much treble energy. Trió ups both pace and contrast, and unlike Nio’s more relaxed approach, introduces some foot-tapping energy that brings the music to life. The bass drop is deep and wide, and the drums kick in with agility, epitomizing Trió’s powerful dynamics. Fourté loses none of Trió’s speed, if anything speeding things up a touch. While it adds refinement to Trió’s bold approach, it loses some weight in the drop and some of Trió’s dynamic punch in the process. Noir restores some of the punch, though not quite as forcefully as Trió, and Miri’s violins have a slightly softer edge too, but the bass is big and the stage every bit as wide as Trió’s, with pace and rhythm to spare.
Detail and clarity
At this level I expect all four hybrids to deliver excellent levels of detail and a high degree of clarity, and on the whole they do. It’s only when compared to each other that some fall behind the others. There’s no inherent lack of detail in any of the hybrids; I find mostly all the fundamental details in a recording are fairly easy to pick up, even with my less-than-perfect hearing. But the flagships, Fourté and Noir, really exemplify the meaning of world-class detail retrieval, picking up subtle cues in the music I imagine some artists didn’t even know were there. Check out my track notes for Amber Rubarth for an interesting example of how this extra detail can sometimes put a completely different spin on the music itself.
Nio
There’s usually a price to be paid for a warmer tuning with dominant bass, and in the case of Nio (M15), that price is detail. Nio’s bass notes are softer than those of the other hybrids, with more rounded edges, and while texture is still very good, it’s not the most detailed bass of the bunch. Despite having six dedicated midrange drivers and one mid-high BA driver, Nio doesn’t quite reach the level of definition of the Tia System hybrids, and while clarity is still very good, with only marginal bass bleed into the mids and even less so with mX, it comes across as slightly veiled when compared to the others. Treble is where Nio picks up some extra detail – the Tia driver not disappointing in this regard – but it’s a more relaxed experience to the other three IEMs. Switching to mX does improve overall clarity, with details veiled by the M15’s bass at least partly revealed (especially in the mids), but there’s not much extra detail to be had in the bass or treble despite the clarity improvements.
Trió
When it comes to outright detail and clarity, Trió is technically outstanding. This is probably the biggest audible difference when switching from Nio (in either configuration) to Trió. Note edges are better defined, with more tonal nuance, and softer cues and subtle effects are easier to make out. While not the fastest of the group, Trió’s bass is very detailed, and a good amount of clarity in the mids, despite an audible upper midrange/lower treble dip. Treble is clear, detailed and extended, if a bit peaky at times, with detail perhaps a little piercing when recordings are less than optimal.
Fourté
The king of clarity, Fourté is easily the most detailed headphone of any form factor I’ve yet heard. It literally misses nothing. If it’s in the recording, you’ll hear it. Due to mild hearing loss and some tinnitus in my left ear, my hearing is no match for Fourté’s technical ability, and I envy anyone who can take full advantage of Fourté’s seemingly limitless ability to resolve every nuance of a track. Ironically, the same hearing loss makes Fourté a good match for me; its microscopic detail retrieval and crystalline transparency is unforgiving of poorly recorded (or even below average) recordings, though more forgiving than Trió due to Fourté’s extra smoothness.
Noir
I’m not quite sure how, but Noir doesn’t give up much detail or clarity to Fourté despite being warmer, fuller and ever so slightly more intimate sounding. The technical strength of 64 Audio’s Tia System is evident here, with resonance and distortion kept to a minimum and detail and clarity dialed up to stun. I’m not missing anything with Noir, likely for the same reasons I mentioned above (mild hearing loss and tinnitus), but also because Noir resolves so effortlessly. I do hear details slightly differently to Fourté, but that’s because tonally they are very different. You could argue there’s a touch more overlap in the details of more complex music, and instruments aren’t separated quite as clearly from the vocals on bassier tracks, but honestly that’s just splitting hairs at this level.
Daft Punk’s Giorgio by Moroder, off 2013’s Random Access Memories (Limited Box Set Edition), is a perennial favourite of mine for testing the capabilities of just about any high-end system, let alone IEMs. It’s such a versatile track, but I’m using it here to check two things: how well I can hear Giorgio talking amid the din of the crowd in the intro section; and how clearly I can make out the crescendo of the track, where the mix of instruments and effects from 8:04 goes absolutely bonkers. Giorgio’s voice sounds full and chesty with Nio (M15), though not quite as clear as I’d like, but it opens up some switching to mX, and the crowd effects are more delineated too. Nio does a decent job with the finale, but its shortcomings in the detail department are obvious here. The cymbal crashes in the left channel, for example, are a bit muddy, and neither M15 or mX have enough finesse to fully separate the strings, drums and guitars for maximum clarity. The jump in detail between Nio and Trió is obvious as soon as Giorgio starts speaking. The nuance in his voice is far more distinct, though there’s a bit of stray treble energy in edges of his syllables that come across as slightly glassy. Trió’s extra detail in the crescendo is impressive, however, with the instruments better separated and the cymbals more accurate than with Nio. Fourté not only out-resolves Trió with Giorgio’s voice – albeit sounding a little drier and thinner – but it also lifts the detail and three-dimensionality of the crowd, seating you next to him in the bar. Fourté’s clinical precision and pace also makes easy work of the closing melee, with every instrument given ample room to shine without even a hint of blurring. Noir voices Giorgio with more authority than Fourté, but the crowd effects are slightly less distinct. That fullness carries over into the melee, where the instruments left and right are clearly defined but the middle section becomes a touch thicker and loses a bit of clarity in the process.
Rebecca Pidgeon’s Spanish Harlem, from her 1994 Chesky SACD The Raven, is a very delicate recording with some intricately detailed interplay between various instruments and Rebecca’s angelic voice. At the 1:40 mark, a shaker starts to play just to the right of centre, along with a violin to the left and guitar, bass and piano in between. Despite its inherent fullness, Nio manages to capture the essence and position of the instruments very clearly with both mX and M15, mX extracting a touch more detail from the shaker but less weight from the bass. Trió creates an even better sense of space, particularly with the shaker, which now echoes more realistically in the room, and I could actually hear the strumming of the guitar strings, something Nio missed completely. Fourté’s sonic microscope brings each of the instruments into even sharper relief, with even more strumming apparent and the shaker set further back and to the left in a wider stage, creating a better sense of depth. Noir brings the shaker forward again, adding heft to the bass, warmth to the piano, but not resolving the strumming quite as surgically as Fourté.
Jethro Tull’s The Waking Edge, from their 1987 album Crest of a Knave, features an instrumental opening sequence that overlays Ian Anderson’s iconic flute with a mix of guitar strums, stick hits, what sounds like a pipe organ, and possibly one or two more subtle effects, all of which should be clear, crisp and well-defined in their own space. Nio’s rendition is lively enough, but rounds off the edges of some of the sharper instruments more than I’d like. It’s also doesn’t fully resolve all the fundamentals in Anderson’s flute play, nor the finer nuances of the organ. mX improves the level of detail somewhat, making the edges more distinct and the flute nimbler. Trió does a splendid job with the details, the organ, strumming, flute and guitar plucks sounding far more dynamic; though the guitar picks do get a touch zingier than they should at the one-minute mark. Fourté’s presentation is almost flawless; some of the brighter guitar picks call perhaps a bit too much attention to themselves, but still come across more smoothy than Trió’s zing, and Anderson’s flute is so realistic, you can almost hear the rush of his breath through the tone holes as he plays it. Noir cools down the brighter picks, adding a fullness to the flute as well, that makes it less breathy, and is the most cohesive presentation of the lot.
Oh, and here’s an interesting tidbit: Crest of a Knave beat out Metallica’s And Justice For All for the 1989 Grammy Award for…wait for it…Best Hard Rock/Metal Performance, Vocal and Instrumental! No justice at all, considering the album is practically full of folk ballads.
Amber Rubarth’s Tundra, an instrumental track off her 2012 reference-quality Chesky binaural album, Sessions From The 17th Ward, is just one of several tracks on the album that leave interesting ‘Easter Eggs’ in the recording for keen ears (and highly resolving IEMs) to find. If you listen carefully at the 0:40 mark, amid the much louder drums and violins, you’ll hear a wooshing sound in the background, possibly followed by a low rumble and a slight squeal. The effect lasts about 10 seconds, and from what some audiophile friends and I have gathered, is the sound of a truck’s air brakes bringing it to a grinding stop in the traffic outside the recording studio. The sound is audible to various degrees with each of the four IEMs, all of them picking up the initial ‘woosh’ and screech of the ‘brakes’, but only Trió, Fourté and Noir resolving the full sequence at a volume low enough for the actual music not to damage one’s hearing. Both Trió and Noir convince me the sound is made by a truck, while Fourté tells me it’s a blue 18-wheeler with a slightly bent rear axle and three tyres in need of a change.
Having spent several intense weeks listening, understanding and appreciating their relative strengths and shortcomings, it’s fair to say all four of 64 Audio’s high-end hybrids are impressive in their own right. While the scope of this review doesn’t seek to compare them to other IEMs from 64 Audio (and other IEMs in general), I believe the regard with which each of these IEMs is held in the market is justified.
I’ve summarized my personal feelings about each IEM below, taking into account everything discussed so far, but also factoring in the most important factor you won’t find in any measurements: personal preferences. Reviewing IEMs can be a very clinical process that bears little resemblance to listening to an IEM on its own merit, with your favourite music, for enjoyment rather than analysis. Keep this in mind as you read my verdicts, and know that in most cases, how you hear these IEMs will be very personal to you too.
Nio
Nio has a relaxed, easy-listening tonality that’s suited to wide range of genres. It may not win any technical awards compared to its older and more mature siblings, but is, on its own, very technically capable. It also has the ‘latest and greatest’ when it comes to 64 Audio tech, including switchable Apex modules (that genuinely alter its sound profile), LID and Tia, and has more physical drivers than Trió and Fourté combined.
Nio is the most versatile of the bunch as well, and depending on your preferences, could fill the role of two separate IEMs in your collection. With the default M15 module, Nio has a powerful, elevated bass that gives music a warmer undertone, with fuller notes and a more relaxed treble. Detail and clarity does take a small hit, however, as does stage size and imaging, and Nio can feel a touch congested when the music gets particularly complex or busy.
With the mX module Nio is more linear, with bass still playing a role but taking a back seat to the mids and treble. There’s less rumble, and less slam too, but the mids are opened up as a result, with more nimble notes and a more sparkle in the treble. Detail is improved, but not significantly enough to challenge the other IEMs in this regard. The stage does get bigger though, and separation more apparent, and while it’s relatively faster sounding than M15, Nio mX is still a fairly relaxed and very polite sounding IEM.
For me personally, what Nio lacks in technical prowess it makes up for with its smooth, lush tonality. Nio’s warm and richly-textured sound is ideal for female singers, folk, indie and acoustic music. It also does well with vocal jazz, bass-rich electronica and EDM, but might be less suited to faster, aggressive music, or more complex, dynamic classical pieces, with which it might sound too relaxed for some.
Trió
Trió is an enigmatic IEM, and often seems to get lost in the crowd when discussing the virtues of 64 Audio’s high-end IEMs. I’m not quite sure why that is, because Trió is an exceptionally accomplished performer. It may not have the technical mastery of the Fourté or Noir, but it’s not far off, and for some, its combination of energy and dynamism might actually be preferable to the Fourté’s unapologetically precise tuning or Noir’s thicker, more adventurous tonality.
Where Nio goes for a softer touch, Trió hardens the edges, speeds up the tempo, and delivers your music with gusto. Bass is prodigiously elevated, favouring sub bass rumble over midbass bloom, and while mids remain fairly neutral, they’re very clear and detailed, if a little dry. Treble can be spiky, yes, but on the whole it’s smooth and well extended, rewarding well-recorded music with plenty of sparkle and air.
Trió ticks more boxes than it doesn’t for me. Stage is wide with decent depth, though not quite holographic, instrument and vocal separation are both above average, and imaging is always on point. Speed and dynamics are within touching distance of Fourté (which is to say, extreme), as are detail and overall clarity. What Trió lacks, perhaps, is that last bit of refinement. For all its boldness, Trió can sometimes overstep the mark, especially with brighter recordings, or where cymbal splashes and high-register vocals are less than perfectly mastered.
If you’re into EDM or fast-paced music in general, Trió is custom made for you. As a recovering basshead, Trió completely satisfies. It also handles more complex music with aplomb, including classical music, along with acoustic recordings and anything instrumental in general. At the other end of the scale, Trió will just as easily satisfy treble heads, especially if you have a penchant for treble zing. I consider Trió an excellent all-rounder, in particular if you’re after dynamic excitement from your music.
Fourté
Fourté is the best sounding IEM, and possibly headphone, I’ve ever heard – most of the time. With the wrong music, or the wrong source pairing, or tips that don’t quite seal, or a cable that’s too bright, it wouldn’t be the best at anything. That’s the thing with Fourté; like any great Diva, give it exactly what it wants, play to its strengths, and you’ll get the most immersive, expansive, transcendent aural experience imaginable. But if something’s not quite right, it’ll let you know, sometimes painfully.
Fourté is unquestionably the best technical performer of the bunch. It has the widest, deepest and most three-dimensional holographic stage I’ve heard with any IEM, with a pitch-black background, outstanding vocal and instrument separation, pinpoint imaging, laser-like speed, and a unique ability to resolve every miniscule detail in a recoding. More impressive is how effortlessly it manages to do all of this and still sound musical. Yes, Fourté can be used to chop your music into neat little building blocks, but to my ears it’s not inherently analytical.
Where Fourté stumbles, for some, is in its balance and overall tonality. It has a brighter leaning for sure, and while bass can be big and bombastic when called for, it more often than not isn’t. This is not a basshead IEM by any stretch, and despite its bass quality, I personally wouldn’t accept any less bass quantity than this in my collection. Its restraint, combined with an overall airiness in the mids, means Fourté can lack some gravitas when compared to the other, fuller sounding hybrids, but when I’m not comparing, it almost always sounds on point.
What Fourté lacks in weight it makes up for with finesse. While it comes off as brighter than Trió, for example, it’s also more refined. As someone who’s very sensitive to harsh treble, Fourté has the most delightfully smooth treble I’ve heard. It’s something I honestly feared leading up to my first listen, but those fears were quickly allayed. Yes, I’ve heard the unnerving power of its treble – a harmonica too closely micced in a Cowboy Junkies recording quickly brought me to attention – but, when everything is just right, as it generally is, you’ll get no nasty surprises here, no temper tantrums, just gloriously beautiful music.
Noir
Noir is a very interesting IEM, one that I consider an experimental attempt at creating a fuller, warmer Fourté without sacrificing any of its world-class technicalities. On the whole, the experiment works. For those that think Trió is already that IEM, I couldn’t disagree more. Noir is actually more Nio than Trió, with a thicker tonality and more rounded edges compared to Trió’s sharper, punchier sound. But it’s also far less Fourté than the same DNA and driver configuration might suggest. Even their graphs are virtually identical, barring one or two deviations here and there, but there’s no mistaking Noir’s significant departure from the Fourté blueprint.
Technically, Noir and Fourté are cut from the same cloth. The stage, while not quite as wide or holographic, is still immense, imaging and separation are both excellent, it’s fast and dynamic, and can dig almost as deep into the details as its older sibling. Where it differs completely is tonality. Where Fourté is airy and unflinchingly clear, Noir adds a layer of midbass extension that warms up the sound right through to the upper mids. Where Fourté leans its W-shaped tuning to the right, Noir leans it left.
Listening to Noir and Fourté side-by-side is quite disconcerting. Depending on your preferences, it’ll leave you feeling one or the other lacks something, whereas giving each IEM an extended listen on its own irons out most of the ‘flaws’ your brain is convinced it’s hearing. Listening to Noir right after Fourté, for example, left me missing some of Fourté’s clarity, even though I know Noir isn’t veiled. Switching the other way, I missed some of Noir’s weight and denser notation.
Despite the name, Noir isn’t a dark IEM. It is a warm IEM, but balanced by a brighter – sometimes surprisingly brighter – treble. It’s also more detailed and more fleet-footed than a warm, thicker-sounding IEM has any right to be, like a bodybuilder dancing ballet. There wasn’t a song I heard on Noir that didn’t sound controlled, cohesive and musical. From faster-paced EDM to slower acoustic and singer-songwriter tracks, both name and female, I enjoyed them all with Noir. Does it hit the highs, so to speak, of Fourté. No, not for me, but it’s also less prone to throwing a hissy and poking your eye out with a poor recording. Which ultimately makes Noir an easier recommendation for some, especially for those that want the very best with the least amount of fuss.
Closing thoughts
While I made numerous value judgements throughout this review, based on my personal preferences and biases, I also purposefully avoided any sort of rating or scoring, nor did I declare an overall ‘winner’. In truth we’re all winners, and while that might sound cliched, I honestly believe that what we have in these four IEMs is a selection of some of the finest transducers available today, at any price.
64 Audio have designed and tuned all four hybrids to meet very specific criteria, be it easy listening, dynamic excitement or refined sophistication, and yet, depending on your preferences and favourite style of music, each one will give you exactly the same thing: a consistently excellent listen.
This review / shootout is audiophile and head-fi gold! Undoubtedly a gargantuan task which was so expertly executed and incredibly articulated. Methinks a new benchmark has been set.
Although I felt like I just read a doctorate's dissertation, I also agree that this is THE review to read and used to compare the 64 Audio line up. I am fortunate to own two of the models mentioned and all of your observations were spot on. Lastly, I've been having superb and information conversations with your brother, @xenithon so thank you both for being such valued members of the community. Cheers!
What a terrific job putting together a multi-post "piece" that thoughtfully communicates blurbs and impressionss I've read across maybe hundreds of posts! You've given that amorphous blob a sense of organization that I sincerely appreciate.
I've thought that the Trió is the 64 Audio offering that most interests me, and your observations have kind of cemented that for me. Now comes the part of deciding whether I want to spend this much and rob from another of my hobbies' fund to finance it, hahaha.
You really won't regret it. I feel the Trio is kind of the best everyday carry or Swiss Army Knife pair that just excels at everything. Super fun and not picky pair. I hope you enjoy it one day!
As someone who’s very sensitive to harsh treble, Fourté has the most delightfully smooth treble I’ve heard. It’s something I honestly feared leading up to my first listen, but those fears were quickly allayed.
Really nice job on this write-up, and love the photos.
I agree with most of what you say about the fourte and trio (haven’t heard the other two,) but your perspective on the fourte’s treble is extremely unusual.
It’s awesome it works well for you, however it should be noted that it is quite common for those who are sensitive to treble, to have at least some issue with the fourte’s treble. of course, always listen if you can, because your case shows it's possible to be treble-sensitive but still adore the fourte treble.
edit: fwiw - i love the fourte and think it's 64s most enjoyable sound sig i've heard. the treble def does get a bit hot to my ears at times...that said, i absolutely agree that it sounds magnificent if it doesn't rub you the wrong way.
Congratulations on the completion of such huge work, this was a no easy task for sure and you devoted a lot of time and soul energy for this content.
For me this tells a lot as you chosen the 4 best iems that are present on the market. Non doubt there is good options for different folks...
But those 4 are the absolute best in each segment that they are positioned!
The fact you decided to share and invest such compassion for them shows and proves that they are the best and really game changers in some ones life who really takes audiophile world seriously and it is hes life and the only way to survive )
I will fully read your review later as that is so much work done that requires every little attention and careful read!
As a master Mr. Tiger ears my self and with huge compassion and love for this hobby like you are too.
I feel the 2 ultimate best iems are the 2 fourté ! Nothing does what they do and time has passed and shown their full poweress on top the rest that is available.
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