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FiR Audio’s House of M: The M5 – An In-Ear Monitor Review

DISCLAIMER: FiR Audio and Project Perfection provided me with the M3, M4 and M5 in return for my honest opinion. I am not personally affiliated with these companies in any way, nor do I receive any monetary rewards for a positive evaluation. I’d like to thank FiR Audio and Project Perfection for their kindness and support. The review is as follows.

Last, but unequivocally not least, we have the M line-up’s statement piece: The FiR Audio M5 in a blazing, hotrod red. As previously mentioned in Prologue, this five-driver flagship has my second-favourite colourway of the three. Though I tend to prefer darker reds, the vibrance of this shade is undeniably stunning. And, as the photos show, they pair exceptionally well with Focusrite’s Scarlett interfaces too. Again, this M5 boasts FiR’s gorgeously-crafted, machined-aluminium chassis. Then, in addition to Direct Bore, ATOM and Tactile Bass, they’re also the one model in this line-up to implement Direct Bore electrostats. As you’ll see, all this tech combines to create what is, to me, FiR’s most technical and most musical piece yet.

FiR Audio M5

  • Driver count: Three balanced-armature drivers, one dynamic driver and one electrostatic driver
  • Impedance: 6.8Ω @ 1kHz
  • Sensitivity: N/A
  • Key feature(s) (if any): Direct Bore drivers, Tactile Bass technology, ATOM pressure release system
  • Available form factor(s): Universal aluminium and custom acrylic IEMs
  • Price: $2799
  • Website:

This review is a part of FiR Audio’s House of M series and will only cover sound impressions. For the introductory article covering packaging, accessories, build and fit, as well as FiR Audio’s slew of proprietary technologies, click the link here.


Despite the M5’s pretty diverse driver config, it has, to me, surprisingly come off the most cohesive, refined and well-put-together of the three M IEMs. There’s this distinct effortlessness and finesse to it, which really shines through in how tidy its stage is organised, how crisply-separated its layers are and how precisely you can hear individual notes start and end. That authority, clarity and control throughout its frequency response are the M5’s greatest strengths to me, along with a brilliantly open, airy image to go with it too. It expands far along all three axes with instruments lining more so the outer reaches than the centre. This airier, more expansive imaging slightly leans this M5 more towards complex arrangements than soloists. On Lucy Rose’s Floral Dresses, for example, I’m drawn more towards the air in the track, the clarity of all the instruments and how cleanly-separated they all are, rather than that rawness and emotion in Rose’s vocal performance.

However, that’s not to say this M5 isn’t capable of revealing emotion either. For its lack of cuddling intimacy and warmth, I’ve found the in-ear is interestingly capable of storytelling through its precision and dynamic range. On Floral Dresses, for example, the frailty in Rose’s performance is aptly captured in how small her voice is within the track’s huge soundscape. Conversely, Jennifer Hudson’s torrential force on I Run occupies the entire image. So, though the M5 isn’t an earphone I’d necessarily call cozy, it’s still one that’ll deliver musicality in spades because of its technical feats. Onto the IEM’s timbre, it qualifies as neutral to my ears. As per the FiR house sound, this M5’s crisp, refined highs and quick, yet hearty lows sort-of meet in the middle. And, the midrange has great presence to it too. So, despite that grander, less intimate imaging, leads will still have tons of vibrance, zing and punch to them, and notes’ll rarely ever feel compressed, hollowed or sucked out.


While we’ve had a tighter, cleaner low-end from the M3 and a fuller, gutsier one out of the M4, the M5 sits somewhere in the middle. It’s definitely more like the latter in body and texture, but kept more in-rein in presence and punch. The mid-bass isn’t as expressive or loose on songs like Dua Lipa’s Levitating or Oytun Ersan’s Oh, That Butterfly! But, you will hear a cleaner, airier stage in return, as well as a more precise sound overall. Obviously, whether or not this’s a good trade shall ultimately depend on your tastes, but that’s what multi-flavoured in-ear line-ups are for. It’s not a bass that’s ever lacking either. The intro to Frank Ocean’s Nikes rightfully thumps, and the subs really come to life on Tom Misch’s Lift Off or Tone Stith’s Birthday At Midnight. It’s a testament to the IEM’s excellent bass extension, which gives it gumption, physicality and drive in spades. It’s a virtue of the bass’s size as well. Kick drums, while controlled, don’t ever feel choked or compressed. While reined-in, they’ll always sound lively and massive, but with the finesse to keep all eyes (or ears) on the lead as well.

In typical FiR fashion, the M5’s bottom-end showcases superb quality; rich in texture, piston-like in its physicality and yet, incredibly agile too. This is a bass that kicks and dips, which, again, benefits the cleanliness and airiness of the image. It’s most apparent in its mid-bass, where it doesn’t linger and permeate as much as the M4’s, for example. But, in the time it does have, it’s capable of squeezing out lots of detail nonetheless. Kick drums have their thump and thwack fully realised, and toms are similarly resolved down to the tails. This is further boosted by the low-end’s striking dynamic range; readily making those instruments really hit and expand when needed, but in a controlled fashion, once again. The single sound that, to me, doesn’t really benefit from a quicker mid-bass is the acoustic or upright bass. The M4 is better at parsing out those warm, woody notes on, say, Sarah McKenzie’s At Long Last Love. But, again, this’s down to taste. Either way, when it comes to bass chops, this M5 has it in spades: Depth, dynamics and detail that’ll make any bass section shine with grace.


Of the three M in-ears, I find this M5’s midrange the best balanced, the best resolved and yet, the smoothest too. There’s still that slight tilt towards its higher-mids for vibrance, presence and pop, but it’s the lightest lift of the lot. The coherency it maintains is superb, and instruments are given a beautifully-rounded tonal profile as a result. Snare drums flaunt both their crackle and their depth, brass sections are evenly-sat across the board, and singers – male or female – never sound breathy or hoarse. They’re all vibrant, expressive and sufficiently meaty. And, they’re very precisely separated too. Again, the M5’s instruments always sit well-arrayed with very little overlap; crisp air freely coursing between them. But, perhaps because of this IEM’s tubeless design, what I love most about the M5’s midrange is how this separation co-exists with its smooth, slightly rich tonality. There’s a wetness – a glow – to these mids that work wonders for pianos and violins, among others; an analog hue that dissuades coldness, and a mix of precision and soul that I feel the M5 nails to excellent effect.

When it comes to positioning and imaging in the mix, again, this M5’s mids land around where I’d call neutral. They won’t get drowned out by busy bass lines, nor are they ever lost behind open hi-hats or crashes. At the risk of sounding vague, I’d call it a versatile, safe, just enough sort of midrange that sits squarely in the ensemble, and I expect it’ll only be disliked by those who’d prefer either extreme. If you like instruments incredibly intimate and lush, the M5 may come off a smidge more precise than you’d like. But, at the same time, it has more meat than what I’d call clinical too. So, to me, it sits in the healthy in-between where it sounds present, rich and clear with any genre, even if it doesn’t go the extra mile in emotion and resonance, which we discussed in Presentation. However, as discussed in that very section, this IEM is still capable of making those mids shine when called for. The monitor’s linear, natural tone gives credence to lower-pitched instruments like the baritone sax more so than its siblings. Plus, despite its penchant for precision, it’s capable of superb building too. The escalation throughout the keys-and-guitar part of Oytun Ersan’s Mysterious Maze is a fine example. So, as long as you don’t mind a less intimate, less enveloping feel, this M5 will show you precision and balance with dynamics and soul too.


The M5 sports a lower-treble not unlike the M3 and M4; peaked at 5kHz with a crisp, yet refined bite, before tailing off so there isn’t that hard-edged metallicity that’ll typically cause harshness or fatigue. Again, like its brethren, it’s an articulate peak that hands hi-hats and cymbals their crucial bits of cut, and it’s wonderful with snare drums or string plucks as well; transients leaping off the backdrop with punch. But, where it diverts from (and improves upon) the M3 and M4 is in how that peak is supported. The M5’s richer, more organic lower-mid tuning cushions the treble better, so there isn’t as far of a gap between the transient and the harmonic. It resolves that dryness I found on the M3, and it feels more genuine than the M4’s upper-bass rise towards the same goal. Though it’s the technically the work of the mids, it does ultimately make the M5’s low-treble peak more palatable to me, as everything connects in a smoother way. So, though this M5 doesn’t do much different with its low-treble, it has been better facilitated, allowing it to better integrate and shine at the same time.

Higher up the treble is where this M5’s electrostats start coming into play, and it delivers a slightly different presentation as a result. Though the M5 shares the M3 and M4’s slight shelf or taper, which results in that same sense of smoothness, subtlety and refinement, those e-stats do lend an effortlessness those two didn’t quite have. While you might find similar amounts of air in the M4, the M5 renders them with greater ease, resulting in a more open, more floaty feel to its notes. This contributes to the latter’s grander, less concentrated (or intimate) presentation, and it does wonders for separation as well. Thanks to this top-end’s extra headroom, cymbals, hi-hats, chimes and the like come through cleaner – having to cut through less muck. And, the M5’s excellent stereo spread positions them far apart as well for an incredibly immersive surround sound, especially with more complex material. Finally, again, that slight taper off the highest octaves lend those instruments what I’d consider a natural, even-handed tonality that rides the line between neutral and natural very nicely.

General Recommendations

As you’d probably surmise by now, ths M5 is an in-ear that’s – first and foremost – airy, open-sounding and dynamic, but in a controlled, refined way. It’s overall balance and neutrality make it fairly genre-agnostic; there aren’t really any it can’t work with. Plus, its incredible achievements in separation, resolution and physicality benefit all sorts of music universally as well. However, despite its doses of punch and oomph (especially across the lows), it can potentially come off a tad less engrossing or enveloping at times, especially with simpler, more intimate arrangements. If you need vocals to swathe or engulf you, almost, you may find the M5 a smidge too laid-back and calculated for that. It’s also an in-ear with FiR’s classic low-treble bite, which, even though it’s the most refined version of the lot, should be noted if you’re sensitive to any high-end sparkle. All in all, though, as long you have those two last caveats in mind, the M5 is a flagship that rarely puts a foot wrong to me. As long as the budget fits, it’s a strong all-rounder, especially if you want clarity, balance and punch in tons.

Select Comparisons

64 Audio tia Fourté (USD 3799)

64 Audio’s tia Fourté Noir is an in-ear that shares the M5’s blend of intensity and control. They’re similarly punchy in-ears that’ve successfully encased all their brazen energy into well-organised soundscapes. To me, what separates them, then, is how they’ve each portioned out that blend. The Noir, for example, doubles down on excitement and fun, exaggerating its colourations for a more W-shaped sound. Instruments aren’t as smoothly or evenly structured as they are on this M5, but that’s also given them more attack at the same time. That is especially true of the treble-and-centre-mid relationship, where the Noir’s elevation of the former and reduction of the latter gives its transients tons of contrast, energy and bite. By comparison, this M5’s more linear take on the signature still has excitement to it as well. But, it’s traded some of it off for a more linear response, where a note’s head and body sit on the same plane. On Cody Fry, Cory Wong and Dynamo’s Better, for example, the Noir exaggerates the horn stabs, hi-hats and Fry’s vocals, while this M5 is fairer to the synths and backing vocals. So, tonally, picking between the Noir and M5 will depend on how excited or lifted you’d like the IEM to be.

Then, in terms of individual differences from bottom to top, you’ll get a warmer, fuller bass response out of FiR’s M5. The bass line on FKJ’s Better Give U Up, for example, is fatter, more guttural and it digs deeper at your chest as well. The Noir’s low-end is a hair more even-handed between the sub-, mid- and upper-bass. So, though low notes won’t quite rumble as viscerally as they do on this M5, you will be able to hear more of the note itself, along with each individual reverberation within it. So, it’ll depend on whether you prefer verve or nuance. The mids are where I feel the M5 comes out on top with a more even tonality, greater centre-mid support for vocal structure and a wetter, more natural hue overall. The Fourté’s tighter, drier response comes off more artificial to me, even if that tightness gives it cleaner separation. Up top, although both in-ears sport fair amounts of sparkle and tizz, the Noir does have more of a bite to its mid-treble, resulting in slightly harder-edged transients than the M5. Plosives are a tad more prone to brittleness, and its high-treble peak brightens the backdrop too. Whereas, thes M5’s peaks sit more cozily with the rest of its sound, even if it’s a bit more subtle as a result.

Empire Ears Odin (USD 3399)

The Odin and this M5 are both earphones with emphases on openness and air; both grand in imaging and spread-out in structure. They sport similarly neutral colourations too, leaning neither towards all-out brightness nor gooey warmth. To me, where they ultimately differ is, firstly, in dynamics and, secondly, in how they formulate their midranges. Because of the M5’s more present, more pointed treble, it’s the stronger articulator of the two with sharper transients, tighter decay and a slightly brighter shimmer to, say, cymbals. The contrast between that and its low-end gives the in-ear the punchier, more energetic signature. And, details are more apparent at lower listening levels too. By comparison, the Odin’s slightly more refined, more subtle low-treble sits its articulation a tad further back and gives greater focus towards the mids. For example, Yolanda Adams on Nathan East’s Feels Like Home will sound chestier, richer on the Odin, while the M5 sharpens her enunciation, places more of a focus towards her throat and mouth, and emphasises her belt near the climax as well.

While projection, intensity and bite are the M5’s specialty, the Odin’s – as suggested earlier – more so lie in the midrange. It possesses the bigger, more enveloping-sounding vocals, which deliver the intimacy and resonance I’ve said the M5 can lack throughout this review. Though, as mentioned above, they aren’t articulated or enunciated as sharply as they are on the M5, they do have this vibrance and mass that soar with, say, Mark Lettieri’s electric guitars on Spark and Echo or Cory Henry’s synths on Snarky Puppy’s The Curtain. Instruments radiate in a way that may make the M5’s feel a hair truncated. The same is true for the bass. This M5 aims more for tightness and control; again, limiting the warmer, woodier tones on an upright bass or the decay on a kick drum. Whereas, the Odin delivers the more visceral, more imposing bottom of the two. Bass hits dig deeper, and they linger a bit longer too. The latter lends the edge in bass resolution to the Odin too. In terms of imaging and space, the M5 has the lightly deeper stage to me, and its tighter notes give it more precise panning as well. Though, again, when it comes to imaging to immerse or envelop, the Odin’s more ideal. So, for me, the Odin gets a nod if you want expansion, clarity and intimacy in one, while the M5’s staccato sig is for those after order and precision.

Jomo Audio Trinity (SGD 3799)

Across all the in-ears here, Jomo’s tri-brid, flagship Trinity is perhaps the most like this M5 in tonality. Both are almost W-shaped, and both skilfully balance musicality with precision as well. Another common trait between them is a palpable 1-2kHz rise, which lends instruments a strong spine and almost serves as the bedrock for all the energy flying about above and below. That energy across the extremes is delivered pretty smoothly and linearly as well; never straying too far away from neutral no matter the genre. Ultimately, though, what separates them for me is technical ability. Swapping between the two, FiR’s M5 reveals a clear edge in resolution, definition and focus; instruments seemingly more zeroed-in, cleanly-etched and tactile – physical in nature – than those on the Trinity. The latter, by comparison, can come off a touch hazier, especially with regards to its centre-image; less tight and precise than the M5’s. Its treble, though superbly articulate and clear, also doesn’t extend or float as well as this M5’s can. So, technically-speaking, despite its inherently good technique, the Trinity does fall a tad victim to age; losing out on the technological refinements that the M5’s been privileged to have.

Delving deeper into the finer differences between their respective tonalities, you’ll get a slightly fatter mid-bass on Jomo’s Trinity, with not as much sub-bass. The bass line on Joji’s SLOW DANCING IN THE DARK, for example, will come off rounder – more bulbous – and almost convex in shape. Conversely, the M5’s sub-bass tilt gifts it a darker, rumblier, more physical low-end, with stronger texturing and extension as well. That roundness or bulbousness extends to the Trinity’s mids too, which, despite being similar in tonality with the M5, is quite a bit less focused and tight. Notes are allowed to radiate and intermingle, almost, which certainly seems musical and immersive. But, again, the trade-off there will be in precision and separation. The Trinity’s midrange also isn’t as dynamic and tactile – physical – as the M5’s; again, hazy is the word I’d use here. That lack of dynamism actually has a lot to do with the Trinity’s highs, which miss an inch of reach compared to the M5’s. While the former has space and air for sure, it doesn’t quite let notes breathe as easily as the FiR flagship. So, again, though the two share lots in common tonally, the M5 does come out the stronger performer of the two by virtue of tech.

Vision Ears ELYSIUM (2900 EUR)

Immediately, what separates the ELYSIUM and M5 is the low-end. While the former pushes more tactility and depth than most, single-BA woofers I’ve heard can, it simply can’t measure up to a genuine dynamic driver in texture, physicality and drive. The kick on the A-section of Anomalie’s Le Bleury sits a tad behind the synths in intensity, for example. Whereas, on the M5, they pop in and out of the lead spot as I think this track demands. They span larger too; like a looming silhouette behind the keys. Though, if you happen to prefer a lighter, daintier sig, the ELYSIUM’s presentation would be nice. But, in terms of sheer technicality and realism, lows go to the M5 in my book. Now, in the midrange, the tables have completely turned. This ELYSIUM’s HALC-powered midrange hands vocals a radiant, ethereal quality, along with bounds and bounds of texture. Guitars and keys have a soulfulness to them that’s accompanied by a similar precision as this M5, which I feel is a great feat. But, the gap isn’t as big in detail and power, which the M5 has in spades too. Furthermore, the FiR flagship has more 1-2kHz content, which gives instruments a bolder, weightier timbre. So, really, it could be up to preference too.

Up high is where these two in-ears are most alike. Both employ 5kHz peaks for articulation, followed by a comparatively more relaxed upper-treble for balance and refinement. The one difference I’m picking up is a slightly harder edge on the M5, due to its brighter 8kHz presence. Hi-hats have a thicker, sharper bite when they attack, which contributes, again, to that IEM’s intensity and fun. By comparison, the ELYSIUM feathers its mid-treble for a slightly softer attack, which retains balance at the situational cost of pushing those details forward; you may like one, or the other. High notes are also a tad smaller and tighter on the ELYSIUM as a result, which further boosts that airy, floaty feel I described in the Treble section. But, again, you may prefer the more intense presence of that M5 for genres like rock. Top-end extension is where things get a bit hairy. The ELYSIUM has the potential to best the M5 in effortlessness and stability with more powerful sources. But, when they go head-to-head on, say, the single-ended output of Lotoo’s PAW Gold Touch, it’s more of a toss-up. So, it ultimately will depend on what you drive it with. All in all, I’d say the ELYSIUM and M5 fill fairly similar gaps. One is lighter and daintier with a vocal focus, while the latter is heavier, more driven and more bass-emphasised. It’s all down to taste.





Church-boy by day and audio-obsessee by night, Daniel Lesmana’s world revolves around the rhythms and melodies we lovingly call: Music. When he’s not behind a console mixing live for a congregation of thousands, engineering records in a studio environment, or making noise behind a drum set, you’ll find him on his laptop analysing audio gear with fervor and glee. Now a specialist in custom IEMs, cables and full-sized headphones, he’s looking to bring his unique sensibilities - as both an enthusiast and a professional - into the reviewer’s space; a place where no man has gone before.


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