Up in the Air: FitEar’s hybrid IEM gives you wings


“Maybe you’re the Jerry Harvey of Japan!” Keita Suyama, CEO and Founder of Tokyo-based IEM manufacturer FitEar, seemed somewhat unwilling to accept my compliment despite the almost incontrovertible evidence: that FitEar supplies custom in-ear monitors to hundreds of Japan’s biggest rock and pop stars; that he prides himself on his IEM’s sound quality; that FitEar are big news in Japan’s head-fi scene; that his booth at local headphone shows consistently draw some of the biggest crowds; that demand for FitEar’s handiwork is so strong that wait times between ear-mould appointment and custom IEM delivery can sometimes stretch out to half a year or more.

Such wait times would seem worth it. FitEar’s latest custom model, the Air, is a highly expressive earphone, particularly in the treble and bass. I’d call them ‘fun’ if that descriptor hadn’t already become a polite stand-in for a U-shaped frequency response.


The Air’s midrange holography says otherwise. Vocals really pop. These FitEars are fun in the way that Zu Audio loudspeakers are fun. The F-word applied euphemistically here to this IEM’s thrill-ride dynamics that don’t lose sight of high-end head-fi standards of refinement and separation. On tonal mass, the occasional rivals’ cook-up will serve more meat.

The FitEars are a modern music lover’s dream come true in that they make everything from Radiohead’s In Rainbows to Richie Hawtin’s From My Mind To Yours sound more exciting and involving than do the Ultimate Ears’ UE 7 Pro. You guessed it: the Japanese ‘phones are more coloured than their Californian rival and all the better for it.

In case you were wondering, Suyama-san is no Johnny-come-lately. Whilst an audiologist, in 2001 he began experimenting with earphone modifications; first a pair of Apple earbuds, then a pair of Shure IEMs.


Fourteen years on, the audiology seemingly plays second fiddle to earphone manufacture. On the upper floors of FitEar’s Tokyo headquarters a room is set aside for hearing-aid testing. To non-audiophiles, the enormous Altecs still point to something else going on. On the floor above, an equally impressive pair of Dynaudios ensure that Suyama-san can play it loud whilst undertaking product development work.

Nowadays though, FitEar can be seen collaborating with the big boys. As per the inscription on each earpiece, the Air are “Powered by Fostex”. The Japanese headphone giant supply the Air’s 9mm dynamic driver.

However, the Air is a hybrid design. The accompanying balanced armature driver comes from Sonion. When pushed on “How many of each?”, Suyama-san plays it coy: “At least one of each”, he says with a smile.

Similarly in 2014, Suyama-san wouldn’t be drawn on the exact number of balanced armature drivers running inside his eponymously-name fitear universal. Like many IEM manufacturers, the FitEar mainman is pushing back against those who would make judgement calls ahead of an audition.

In the case of FitEar however, listening is a long way from easy. A very small number of units see export to Hong Kong, Taiwan, China and Singapore but the vast majority of the company’s custom and universal models are available only in Japan.

Compounding the try-before-you-buy challenge: how does one audition a custom earphone before it is made?

The second of Tokyo’s 2015 Fujiya Avic headphone festivals had the answer. FitEar offered would be punters a chance to try a demo-only universal take on the Air. Miss that and the only option is to visit FitEar HQ.


Located ten minutes’ walk from Ginza’s high-end fashion retail strip, FitEar’s facility is large by local standards but also typically Tokyo: every last square metre of each floor is fully utilised whilst a narrow elevator, whose door opens directly onto each floor (no lobby), carries people up and down. If a stairwell exists, it’s not apparent.

Handling re-introductions this time out was one Kotaro Shima of Emilai (local handlers of OPPO Digital, Aurender and AURALiC among others). Suyama-san’s spoken English is excellent and Shima-san’s translation skills weren’t required, not even once.

One up from street level is where the earphone auditions take place. Suyama-san had laid out the FitEar range across the table. Like his Fujiya Avic show exhibits, universal versions of custom models had been prepared.

One notable takeaway from my Ginza visit was that the sonic deltas sitting between the handful of FitEar IEMs I listened to with a Sony NW-ZX2 were more pronounced than expected. Where earshell volume, shape and disclosed (!) driver count differed, so did tonal balance and dynamic contrast.

I was particularly taken by the Parterre’s more elegant sound signature but it’s a universal. To visit FitEar’s HQ and not go custom would surely be a missed opportunity. Besides, with each pair of custom IEMs tailored to the individual, superior isolation from external noise is one key advantage over any universal equivalent. That said, universals have the clear upper hand in the second hand market.

The MH335DW custom, a ‘double-woofer’ variation on the MH334, itself designed in conjunction with mastering engineer Mitsuharu Harada, very nearly stole my nomination on the day. However, the Air’s more radical break from the multiple balanced armature norm ultimately held sway. A hybrid driver configuration, a choice of six coloured faceplates (I went with yellow) and precision 3D-printed earpieces weren’t FitEar’s usual speed.


Silicon gel moulds of my ears were taken on site in Ginza by Suyama-san’s assistant. Afterwards, the waiting game. This pair of Air took around 8 weeks to wing their way to Sydney. Emilai’s Shima-san bridged the gap between FitEar’s Japan-only delivery policy and Fedex International.

In daily use, the Air’s shorter nozzle – that FitEar refer to as “short leg shell” – not only allows for a larger air gap between the twin-bore output and the eardrum, it also renders the Japanese customs more comfortable to wear for longer periods than Noble Audio’s Savant (review in the works). This was most noticeable after short-haul naps on long-haul flights where one ear is invariably pressed against a pillow.

One such flight took place in May. This commentator’s third trip to Tokyo and third sitdown with Suyama-san in six months. Physical evidence of his big news wasn’t to be found at FitEar’s Fujiva Avic show table but at Fostex’s whose all-new TE100 IEM was a universal take on the FitEar Air. A FitEar in Fostex clothing.


The latter’s bilingual promotional material shone a torch onto some hitherto unseen specifications. Impedance = 17 Ohms. Sensitivity = 108dB. Like its custom cousin, the TE100 ships inside a Pelican case that also contains a mesh carrybag and cleaning brush – signs, along with the 3D-printed shell, that FitEar themselves were handling production of the Fostex model.

Fostex have set pricing on the TE100 at ¥115,000 (~US$1100), a few thousand shy of FitEar’s custom AIR which, despite the ‘open price’ obfuscation of their website, sell for ¥135,000 (~US$1300).

Those are big numbers. Thankfully, each earphone’s performance/dollar quotient holds up to closer scrutiny with the Fostex variant seeing worldwide distribution and so robbing you of the perfect audio-related excuse to finally book that bucket list trip to Japan.

Further information: FitEar



Written by John H. Darko

John lives in the NOW + HERE = NOWHERE. He derives an income from the ad revenues of DAR. John is also an occasional staff writer for Stereophile, 6moons and TONEAudio.

Twitter: DarkoAudio
Instagram: DarkoAudio
Facebook: DAR


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  1. Very interesting review John. As an owner of the UE 18 customs I’m wondering if the fit ear is more of a TH900 flavour without the mid suck out and the UE 18 is more of a HD800 flavour?

    That looks like a pioneer exclusive turntable in the video – seriously hi-end analog!
    What are the speakers playing in the video John? They sounded very decent despite the clutter!

    • They’re a Dynaudio something or other. You could ask Suyama-san directly. He’s on Twitter as @kindo3 and his English is excellent. 🙂

  2. As a MH335DW owner (and I absolutely love them), the Air had me intrigued since it was announced. Sadly, I haven’t had the opportunity to get an audition. The slight U-shaped character you describe seems to be consistent with impressions I’ve read elsewhere, but what I worry about is the brightness in the treble and upper mid section, particularly with less than stellar recordings. That’s one reason why I picked the MH335DW back when I auditioned it against it’s FitEar family (Air hadn’t been released back then) and other customs from Noble, Spiral Ear, JHAudio, etc. The 335 might not be the absolute last word in pure resolution, but it’s darkened yet contrasty character proves quite forgiving with recordings that would otherwise render too sibilant on other headphones. That and it’s bass texture is the best of any in-ear I’ve experienced, bar none. What’s your take on the Air in this regard, John?

    • Hey Gan. I find the Air more hardware-dependent than source material dependent. A little too bright maybe with some stuff via the Sony NW-ZX2 but absolutely spot on the money with the Xduoo/FitEar 442 DAP, which I’d rate as one heck of a combo. I’m certainly with you on the bass textures though.

      • Thanks John. Looks like I need to get my paws on that 442 DAP. Any idea if FitEar tweaked the donor Xduoo model to better match their own in-ears, or is it just a standard re-branding plus markup job?

        I assume this is your first custom? How’s the experience been so far, compared to other universals you’ve owned or long-termed in the past. Comparisons to the Campfire models you recently reviewed would be nice.

        Lastly, I always figured you to be a red-n-black kinda bloke. Yellow does look good though.


        • And you’d be right about the red and black which is PRECISELY why I chose to buck that trend with yellow. The 442 is a re-brand – no internal mods – with custom boot screen. However, I’ve Rockboxed mine to get gapless playback.

          Not my first custom. Got a Noble Savant review in the works and a pair UE Pros – both mentioned in this FitEar post. 😉

          • Thanks again. I figured the Noble and EUs were either review units or universals. I had no idea Rockbox was still in use for newer DAPs. Good to hear.