IKKO GEMS OH1S Review: Not another OH sibling


Crisp and clean bass-mids-highs, Good resolution, fast attack, Good imaging, ”refreshing” neutral signature, nice packaging


Bodyless bass, thin timbre, cold tonality, the treble can have too much presence, intimate soundstage, compressed layering, a bit artificial sounding, awkward oval-shaped nozzle, not competitively priced

TONALITY: 7.5/10



IKKO is a company that offers different type of audio products including portable dac-amp, audio cables and desktop speaker (in the futur), but that specialize in earphones offering like their best seller OH1 and OH10 hybrid iem. All IEM from OH serie use a single dynamic driver plus a Knowles balanced armature, and while the OH10 upgrade was mostly about shell material change (full copper) that slightly inflict on sound rendering, the latest OH offering, the GEMS OH1S, have a whole new dynamic driver and different tuning.
Since the OH1 and OH10 tuning was very well balanced and dynamic, did the new tuning choice is good news or bad news? Let’s find out in this review.



As always, the boxing presentation is very tasteful with IKKO, while it uses manga’ish imagery, it isn’t waifu, it’s more creative and playfull. The whole package design is carefully thought and more than worthy of it’s price range. In term of accessories, you have a generous amount of ear tips, a so so cable and a so so leather carrying pouch. If you find the ear tips strange, it’s because of the oval nozzle of the IEM, which is a questionable design choice I will talk about later.



IKKO OH series was all metal until the GEMS which is about half metal half plastic, which inflict on lighter weight. The size is drastically smaller than older siblings too, about 2 times. As well, gone is the 2pin connector for an MMCX one. The housing design is supposed to use special acoustic components to improve the overall sound, but due to very different tuning, it’s hard to make any conclusion about this lower distortion acoustic theories.
Fact is : the OH1S look and feels cheaper than OH1 and OH10, while it’s smaller, the awkward oval nozzle shape make the fit more capricious…especially with included ovni silicone ear tips. Sure, it’s way smaller so at the end you don’t feel the IEM as much, but with my ears shape, the OH1S doesn’t stay still. My ears don’t have oval hole but round one.


I don’t know what to think about the design choice of this OH1S, apart from that IKKO seems to give too much thinking about the design exclusivity and not enough about proper sound production. The cable included is underwhelming and something we would expect from a KZ IEM, not a 200$ one.


While the package and all superficial aspect of it is impressive, the practicality of the product isn’t. This nozzle shape choice was an error that will pull off a lot of potential users.


(using Xduoo X20, Xduoo XD-05plus, Audirect BEAM2 and LG V30)


Mature neutral with lean light bass, smooth mids and crisp treble. Timbral balance is organic, and overall presentation is near analytical due to extra emphasis of highs that is the most energic part of the spectrum.

Thin with good transparency, realist but slightly clinical, the texture is there but not boosted.

Above average, apart from bass that can be hard to see (or feel), it’s very clean and detailed but some areas feel scooped.

It’ all about deepness here, which is good due to the clean bass and black background. Wideness is subpar for the price and tallness isn’t really there, in other word: the sound feel a bit stock in your head.

Quite good, more in instrument placement and accuracy, not so much in ‘’vertical’’ amount of sound layers. Though instrument separation isn’t the widest, it’s clean and accurate.

Lean, very very lean, but well extended in a dry, bodyless way. You can hear the rumble and lower bass line quite clearly, but it’s mostly due to texture and definition. This will not affect the tone of electric bass, but acoustic bass will struggle to sound right and not distant. Control and articulation is quite good and no surprise that you don’t have any bass bleed cause their no slam nor kick weight, again, it’s more an ‘’image’’ of sound than a proper low end that use air to make sine wave. Personally, this type of bass makes me listen music in a overly ‘’cerebral’’ way, emotionally distant but intellectually curious. This low-end presentation is not for bass lover, even those that like it balanced and not boosted, Hzsound Mirror feel like a basshead IEM compared to the OH1S. Some monitor speakers have similar bass to this, or think about a less bodied and textured Sony MDR7506 bass and your not far from it.

Smoothly bright, gently boosted, inoffensive yet vivid enough and well resolved, this is pure balanced armature mids done right. No sign of sibilance, a bit organic and far from being thick, lush or romantically colored, the mid-range doesn’t try to hook your attention and is deadly serious in a good way we can say. Female vocal are particularly well done, less aggressive than older OH models, no sign of sibilance and very clean presence without over abusing pina gain. What the mid-range lack is surely due to it’s need of lower harmonic, the weight isn’t their at all, as well, it isn’t very open and quite intimate in rendering: no wide sound layers floating around, it’s all pin-point and centered, so, everything sound kinda distant without being recessed, vocal being an exception as well as saxophone. Piano sound a little artificial, but this change when you go in high register, in mids the lead attack isn’t hit but shot at you, since the piano use hammer to produce sound this ain’t right. Violin is even worst because it doesn’t improve in the high register, timbral balance just doesn’t work for it.

While everything is rather smooth, the treble take it’s revenge and inject a good dose of energy to overall lean tonality. It had air and space too, which is great. But it can feel a bit detached some time, lacking fullness and complete extension to offer natural decay and sparkle. The attack is very fast and snappy and level of micro-details it dig is quite good…but i feel I have heard this treble in alot of multi BA or Hybrid, and to be honest it doesn’t impress me anymore. It’s a bit capricious, rarely it will go shouty but when it did it cancel any emotionality in me. Thats the thing, without sparkle the upper highs are a bit dull, and here it cut fast in extension so it scoops some important sound info find in natural resonance.

Pretty pretty good. All crisp and thighs. The fast attack that is well controlled, with good snap. The resolution is clean, which is a big plus for proper imaging. Bass control is good and texture, resolution too though sometime it’s distant in the back. The OH1S put its technicalities upfront to achieve a reference mature tuning, so acoustic properties are excellent.

Side notes:
These do not benefit from big amping. Cables upgrade can thicken a bit the sound but doesn’t change anything drastically. Using non-oval ear tips can help to open the sound a bit, so don’t lose hope with the one included!



VS IKKO OH10 (1DD+1Knowles BA-180$)

Unlike the OH1 and OH10 which are similar, the OH1S isn’t at all, well, apart from BA timbre to some extend.
TONALITY is colder and more neutral as well as smoother in mid but more emphasis in treble up to 10khz. OH10 is notably more bassy and has an overall thicker timbre and weightier dynamic.
TIMBRE is more artificial and bright.
SOUNDSTAGE is notably smaller but a hint deeper, it’s less holographic and circular.
IMAGING is cleaner and more accurate and precise.
BASS is a ghost compared to OH10, a ghost that doesn’t haunt you, way flatter and less natural.
MIDS are smoother and less forward, less bodied, cleaner and more detailed.
HIGHS are sharper and more snappy, better controled but not as well balanced as OH10.

All in all, the OH1S make me appreciate my beloved OH10 even more. Even if the resolution isn’t as good as OH1S.

VS SEEAUDIO YUME (1DD+2 Knowles BA-170$)

TONALITY : Warmer, more bassy, smoother Harman target vs crisper diffuse field for the OH1S.
TIMBRE : Thicker, more natural, less dry and bright, darker and less textured.
SOUNDSTAGE : Notably taller and wider, more holographic and out of your head but less deep and clean.
IMAGING : Higher amount of sound layers, less compressed but not as clear in instruments cue and separation.
BASS : More sub-bass boost, thicker body, warmer definition, more weighty slam and better low extension. Sub have more rumble and kick drum are punchier, but bass isn’t as tigh, lean and clean.
MIDS : Fuller sounding, more boosted in presence, lusher, female vocal are more upfront, timbre is more natural, piano note are more weighty, clarity isn’t as high, attack is less edgy.
TREBLE : Smoother lower treble, more organic, fuller and warmer in timbre, less metallic sounding but a bit less snappy and brilliant than OH1S.

All in all, Yume tonality is more relaxed, lusher, smoother and more enjoyable, while OH1S sound colder and more technical, with higher resolution and better attack control.


For me, Audiophile hobby is all about enjoying musicality before technicalities of my music, with the IKKO OH1S, it’s all about technicalities to a point some will find it too clinical sounding, other lacking bass and fun. While the OH1 and OH10 find the organic balance between lush tonality and weighty dynamic technicalities, the OH1S choose to focus on high resolution and neutral tonality. This mature tuning isn’t mass appealing and will please a niche market for those that enjoy neutral diffused field tuning. If you search for fun, Harman target or balanced bassy tuning, the OH1S isn’t for you, but if you want to enjoy your music without any blanket on it’s resolution, any boost in it’s bass or warmth and density in its timbre, this might be the unique GEMS you were waiting for!


PS: Big thanks to IKKO for sending me this review sample and letting me share my honest unbiased thoughts.
You can buy the GEMS OH1S for 199$ Here.

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