Review : Fearless Audio S6 Rui – with a Bang


Highs : fast and addictive. Some IEMs can become tiresome due to aggressive or harsh highs, but that’s never the case here. Sure, sometimes you can feel this little push at the back of your head, just enough to liven up the sound and not too much so you want to dampen it.

Good test-track: Life is beautiful – Quart

Mediums : lush and accurate. For an IEM sold at this price, it’s hard not to fall in love with the mids. Voices are poised, gliding swiftly to your ears, leaving you refreshed after each listening session. Acapella or Jazz is a cake walk, old rock sounds like a garage band (which they were) and it goes on and on…

Good test-track : San-Francisco Street – Sun Rai

Lows : deep and strong. Last point, let’s talk about the bass. Not the lows, the deep, bad, bass. Even if you’re not into it, the Fearless S6 are a must try, really. It doesn’t go as low as a dynamic driver could but the texture, speed and sustain/decay are, by far, superior. I’m usually not into hip-hop, I’d rather go for electro, but the S6 made me change my mind. Big bass, when you need it, and exactly how you want it.

Good test-track : Testify – Awkwafina

Sensitivity / Hiss

The Fearless Audio S6 Rui is very easy to drive but that should not stop you from hooking a good DAC/DAP to it. It’s not a hissy one but as always, try to avoid noisy sources, as much as possible.


Fearless S6 + Cowon Plenue D2 : the Plenue D2 is much more powerful than you would expect, I found myself at very high volume in no time, like a race car. It’s a good association with powerful mids and strong lows. Highs were a bit more recessed than I expected, but sound was still an upper class above what you get from the FiiO M6.
Fearless S6 + FiiO M6 : it’s very good but you find the limit of the FiiO. If the signature is more neutral than the Cowon combo, the soundstage is narrower and you lack the 3D depth found on the Plenue D2. Good for on the go, but less so i better conditions.
Fearless S6 + Shanling M2X : I found it to be the best combo, yet. Soundstage regains its spaciousness, the lows gets lower and there is stronger sense of integrity overall. I really liked the lower-range of the spectrum : crank up the volume and it gets very, very, addictive.


A classic now, it’s comparison time

BGVP DM6 : direct competition, even more if you take account of the price. Technically, I found those two IEMs to be very close and in an A/B comparison it’s hard to favor one on this alone. Once you dig deeper, the Fearless S6 takes the upper hand with stronger lows and better accuracy. It gets palpable once you move to high-tier DAC like Astell&Kern, it’s just more potent.
Hidizs NF-3U : those two IEMs stand at the opposite side of the scale. The NF3-U favors the highs where the S6 takes the low. This could be two options in an audiophile wardrobe, leaving you options depending of what you want to listen this day.
Hifiman RE800 : I really like the RE-800 sound, it gives you clean highs and large dynamics without compromising on details. The Fearless are even more accurate but the RE800 sounds more airy and spacious, this could be a good alternative if you really don’t like balanced earphones.


To sum up, the Fearless Audio S6 Rui is a great IEM, period. It is precise, dynamic, powerful in the lows, accurate in the mids and most of all they do that for a very keen price. For me the price/performance ratio is almost as important as its performance itself. The good news is that nowadays, cheaper doesn’t mean worse, far from there.

The S6 Rui are well-built, comfortable and can even be picked as custom in-ear. Honestly, if you’re a bit curious or are keen to widen your horizon, listen to them. I promise you won’t be disappointed. Fearless audio may have been unknown to me before this review, but now I’m eager to see what comes next. Another addition to the great improbably-named-but-superb-IEMs, together with KZ Audio and BGVP.

4.3/5 - (21 votes)

A nerdy guy with a passion for audio and gadgets, he likes to combine his DAC and his swiss knife. Even after more than 10 years of experience, Nanotechnos still collects all gear he gets, even his first MPMAN MP3 player. He likes spreadsheets, technical specs and all this amazing(ly boring) numbers. But most of all, he loves music: electro, classical, dubstep, Debussy : the daily playlist.


  • Reply April 2, 2019

    Albert Cheng

    I am now very curious about the Y2K amp, the S10 and everything below it

  • Reply April 2, 2019

    Oleg K.

    Are Oriolus Forsteni or iBasso IT04 better than S6 Rui?

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