Review : Fearless Audio S6 Rui – with a Bang


For the nit-pickers and nerdy ones here, I’m giving the specs and technical sheets . For all the others, you can just go to the next page to see how the Fearless Audio S6 performs.

Knowles + Sonion Dual Balanced Armature Drivers

No surprise, the Fearless audio S6 has … 6 transducers. To be fair, there are only four physical drivers inside the shell but two of them are dual transducers from Sonion and Knowles. There is a three-way cross-over mounted on a small PCB and the two high-frequency transducers get their own vent in the nozzle.

It’s a very common typology and dual-armatures have become more and more potent along the years. Back in the days, my first pair of 64 Audio cost me a mere 800€ (VAT included) but now you can get the same configuration for less than half the price.

You get a very classic 2x transducers for bass / 2x transducers for mids / 2x transducers for highs. This should ensure a linear performances across the charts, unless Fearless chose to emphasis some frequencies, but we’ll see about that in a bit. There’s no information on what drivers are used whatsoever, even if my set is translucent, each transducer has been emblazoned with the Fearless name or S6 Rui. Shame !

Full specs

  • Type : IEM / CIEM
  • Style : six driver IEM with three way crossover
  • Drivers : 1x Knowles dual balanced armatures (mid) + 1x Sonion dual balanced armatures (bass) + 2x Knowles balanced armature (highs)
  • Socket : 2-pins 0.78mm
  • Cable : 8N 4 cores OCC silver plated cable
  • Shell : acrylic with extended customization
  • Frequency response range : 15Hz – 20kHz
  • Sensitivity : 113 dB/mW
  • Impedance : 20 ohms

Sound performance

For this review, I only used a set of DAP : the new Cowon Plenue D2 (review incoming), the FiiO M6 (yes again and again) and the new Shanling M2X. I used FLAC files, in 16/24 bits and Spotify when it was possible.

Overall signature

Balanced armature IEMs used to be the norm a few years ago, but now it looks like more and more IEMs are shifting to dynamic and/or hybrid configurations. That’s a bit sad as I tend to prefer balanced IEMs, even if dynamic models I tried were good or just as excellent.

The first listening session of the Fearless S6 Rui surprised me in a good way. It’s precise and fun at the same time, avoiding harsh highs for a more soothing tone. The in-ear never sounds harmful or boring but don’t expect flaming presentation with holographic soundstage. The S6 gives you mellow vibes and gently takes you into his world, instead of pushing you.

Compared to my old 64audio V6-S, the Fearless S6 audio are clearly better, even if it pains me to admit it. Soundstage is wider and adds a nice layer of depth, transients are fast and it’s the kind of ears you could listen to all day. Tonality is always right and I especially like the little bump in the high-mids, giving this rich and dense sonority at every point of the listening session. Again, my old V6S are totally outperformed by those S6 and that’s a good news for you, not so much for me.

Voices are clear and natural, be it Lisa Ekhdal or Diana Krall, the tone always feels right. The strong lower-mids are acting like foundations for the singer, helped by an excellent dynamic range. From low to high, it’s like a Gomorrah knife : perfectly balanced.

The more you listen, the more you like it. The S6 can be impactful when needed, smooth when you want and it reacts immediately to any EQ you apply on your source. When you’re in a hurry, the IEM can play your pep’s tracklist and switch back to slow jazz when you’re idle, with ease. The cherry on top is how great impact sounds when the Fearless are properly driven.

Make no mistake, they may be easy to drive, but the S6 Rui really shines with a good source. Stereo is excellent and on tracks like Andata from Ryuichi Sakamoto everything is in the right place. The keyboard goes left and right, every layer of sound is palpable, the kicks are fast… it’s great.

The review continues on Page Four, after the click HERE or by using the jump below.

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?

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.