Review: Fearless Audio S6Rui – Anthem For The Disenchanted

Why stack knowledge when you can stack drivers?
Why stack knowledge when you can stack drivers?

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A new challenger appears, and he’s a brave one. Step into the ring with the Fearless Audio S6Rui, a six-driver earphone with an accomplished mainstream tuning, hoping to capture your heart, mind, and wallet.

My dad introduced me to professional wrestling (watching, not participating) to instill that violence doesn’t solve anything. And he’s correct, after more than 30 years they’re still at it, when a round of civil discourse could resolve things amicably. They love their fists, theatrics and spandex, so what can I say?

A prevalent storyline in pro wrestling is the top guy holding new talent down, and it gets more obvious when 50-year-old Hulk Hogan is still winning matches against younger, fitter competition. That’s why the New Blood storyline stuck with me, when the new guys banded together to fight the established, older superstars. This was riveting drama of the highest degree.

Eyeing the Torch

Chinese Hi-Fi, of Chifi, is dominated by a few brands, with names like HiFiMan, FiiO, iBasso, qdc and Dunu often bandied about. A few up-and-coming brands plan to usurp or at least disrupt the established order. Step forward Tin HiFi, BGVP, Moondrop and Fearless Audio, stalwarts of the new world order. For the last year or so they have generated some serious buzz with exciting products that sound great and are priced reasonably.

Fearless Audio has been around since 2012, but only went into in-ear monitors (IEMs) in 2016. Since then they have witnessed a meteoric rise with an ever-expanding lineup gaining traction in the mid-to-high-end market. They don’t rest on their laurels, I don’t think they sleep either. Even as we speak they continue to innovate with new products, notably the Paladin Series that uses the fabled Sonion electrostatic drivers aka “the new hotness”.

Why stack knowledge when you can stack drivers?
Why stack knowledge when you can stack drivers?

Fearless Audio S6Rui

“Mention the name Fearless Audio though, and chances are you’ve heard that they’ve done more right than wrong, with a few standout products that might just win pageants. Here, the S6Rui sashays on the catwalk with swagger and sure-footedness that belies its newcomer status. It’s one of the finest V-shaped tunings I’ve heard in recent memory, and puts me in a toe-tapping mood almost instantly.”

What We Like 😍
  • Remarkable build quality
  • Excellent fit and comfort
  • Splendid isolation
  • Accomplished V-shaped tuning
  • Dynamic driver-like bass response
  • Balanced mids tuning
  • Exciting, sparkly treble
  • Tonally competent
  • Coherency
What We Don't Like 🤢
  • Minimal accessory set
  • No cable termination choice
  • Shells might be too big for small ears
  • Bass can be overpowering
  • Subdued upper treble
  • Speed and resolution
  • Tiny soundstage
  • Below average imaging

Six Shots at Fame

Today we look at one of Fearless’ mid-tier models, the S6Rui. Comprising, you guessed it, six balanced armature (BA) drivers per side from Knowles and Sonion, the S6Rui harmonizes the sound via a 3-way crossover and 2 sound tubes. Unique to Fearless is their divided ear mould pressure processing (DPP) technology. DPP promises a more comfortable fit with better sound insulation compared to their peers.

Each S6Rui is painstakingly handmade, and available in universal and custom form, with a host of customization options available to awaken the hidden designer in you. Prices start from $389 for the basic options, but I gotta say, some of their faceplate designs look pretty dang good. The S6Rui can be purchased through Linsoul.

I’d like to thank Lillian of Linsoul for the review sample, and the seamless communication in making this review possible.

Equipment Used:


  1. Sony NW-WM1A “K” Modded, FW 2.0


  1. Fearless Audio S6Rui
  2. FiiO FH5
  3. FiiO FA7


  1. Amber Rubarth – Scribbled Folk Symphonies
  2. Bon Jovi – Cross Road
  3. Ed Sheeran – Divide
  4. Fleetwood Mac – Tango In The Night
  5. Linkin Park – One More Light
  6. Meiko – Playing Favorites
  7. Pet Shop Boys – PopArt
  8. Prince – The Gold Experience
  9. Take That – The Circus
  10. The Eagles – Hell Freezes Over

Technical Specifications

  • Driver: 6 Balanced Armature (1 Sonion Dual Bass BA Driver, 1 Knowles Mid-Frequency BA Driver and 2 Knowles Treble BA Driver)
  • Sensitivity: 113dB/mW
  • Passive noise reduction: 26dB
  • Impedance: 20Ω
  • Freq. Response: 15-20000 Hz
  • Connector: 2pin 0.78mm
  • Plug: 3.5mm
Try saying
Try saying “minimalist” rather than “stingy”.

Packaging and Accessories

Have you ever been extraordinarily late to a dinner party? So late that most of the food has been finished, but your bestie (who arrived early) piled on a bit of everything onto your plate so you won’t go hungry? That was the exact feeling I had while unboxing the S6Rui. Fearless’ packaging has undergone a few revisions based on earlier reviews, but man, what I received seemed like leftovers.

It’s not to say the presentation is horrible. A neat, white cardboard sleeve with the perplexing quote “Classic Never Ends” emblazoned in front greets you. Opening that up, you get a proper Chinese slogan (translated as “may you fearlessly march forward”) with a nice leatherette, cuboid case in periwinkle blue. It’s a semi-hard, magnetic snap-on case with pleasing aesthetics, but I doubt it will withstand the rigors of daily usage.


Besides the case, you get the stock cable, 4 pairs of silicone ear tips in various sizes, a metal warranty card disguised as a spiffy membership card… and that’s it. IEM, cable, tips, case. We’re talking about bare-bones, bare-minimum, bottom-barrel stuff here. I’m looking at the thesaurus for words with similar meanings to “basic”, but I think you get the picture. Not the best way to fearlessly march forward, and completely unjustifiable at $389.

On a clear, warm October night, maybe you can spot the S6Rui engraving too.
On a clear, warm October night, maybe you can spot the S6Rui engraving too.

Design and Build Quality

As mentioned before, you can go absolutely nuts, or flat-out bonkers with the customization options for any Fearless IEM. The S6Rui I was sent has clear, transparent shells, and has a pristine charm to it. Like looking into a skeleton watch, I can see how my S6Rui ticks. From the OCD-like driver arrangement to the neatly-nested internal wiring, crossover units and sound tubes, nothing is hidden as I take a good, voyeuristic look inside the uh, insides.

Fearless Audio IEMs are assembled with enormous care and pride, with the model name engraved on a BA driver in each earpiece. The alignment of each component is nearly symmetrical when you compare left and right earpieces, which is frankly, ridiculous. The transition from faceplate to shell is seamless, and the earpieces are completely free of bubbles. They are immaculately built, and go a long way in justifying the asking price.

If you’ve ever wondered why the Fearless logo is a W rather than a big ol’ F, it’s because fearlessness in Chinese is 无畏 (read as wu wei). The more you know, language fans.


Very little information was released about the stock cable. The only thing I know for sure is the cable is made of 8 wires of Ohno Continuous Casting (OCC) silver plated copper. It’s definitely a step up from conventional cables in terms of wire count and material used, affirming the notion that Fearless Audio caters to the serious audiophile. Ooh.

The cable looks to be built in-house with some good quality parts. The connectors and Y-split look handsome in chrome and silver, while the braiding is tight. For the most part, the cable is a joy to handle. Even with its 8 wires, the cable is soft and coils easily. More importantly it holds its own shape and doesn’t unfurl itself, known as the dreaded memory effect some thick cables are prone to.

Just Vanilla

Currently, the cable is only available with the 3.5mm jack, with no option for balanced connections. Looking at the price tag, I’d love to see more options available for the jack, since many IEM junkies would dabble with 2.5mm or 4.4mm. On the whole, this silvery slithery snake is well done, but for one downside mentioned below.

This little python isn't subtle.
This little python isn’t subtle.

Fit, Isolation, and Comfort

Stuffing BA drivers into an acrylic shell is akin to packing clowns into a Mini, ie. no mean feat. The S6Rui with 6BAs translates to medium-sized earpieces, while the angle of the nozzle helps maintain a good fit and seal. Given the sparse variety of ear tips provided, I’m glad this amorphous blob adheres to my ears pretty well. For people with smaller ears though, try before you buy. You may need aftermarket tips for the best fit.

Once you get a good seal though, say hello to comfy county. The earpieces are lightweight and ergonomic, conferring tranquil enjoyment in your own blissful world. They isolate quite well too, negating about 80% of outside noise. The stock cable, while well-built, weighs them down, and is frankly a bit of overkill. If you switch them out to regular 2 or 4-wire cables, you’d be swinging your head like a shampoo commercial.

Sound Quality

How do you create a hype train? To the best of my knowledge, you wow as many early listeners as possible and let word-of-mouth do the rest. A bit of enhanced bass here, a sprinkling of treble sparkle there, gobs of detail and loads of fun, among others. The S6Rui generated some very positive buzz because of its tuning, and it’s easy to see why. Let’s analyze the sound further.

Overall Sound Signature

Fearless Audio’s S6Rui follows a classic tuning template, the V-shape. Like a novice painter relying on tried-and-tested color combinations (navy/gold has never let me down), you can’t go wrong. The V-shape is vivid, vibrant, full of youthful vigor, and even voluptuous, attractive and arresting to the ear at first listen.

And it’s not just your conventional boosted bass, boisterous treble and buried mids, no.

S6Rui is deceptively well-tuned and gives every part of the sound spectrum space to shine. The details are with the devil, so they say. The bass is undoubtedly elevated for some pulsating fun, as is the treble for some exciting ear-tickling. The mids though, stay where they are and are not recessed. Bass, mids and treble meld together to deliver you a coherent, musical experience that’s hard to dislike.

Listening Conditions

Critical listening was done after 75 hours of burn-in. The S6Rui might be Fearless, but I’ll show them who’s boss. Burn-in did not produce significant sound changes, but I believe the concept of fear has been properly introduced to both parties. The main review rig is Sony’s NW-WM1A Walkman modded by Project K, using the stock cable.

Time for some ladybug bait.
Time for some ladybug bait.


Extra large and in charge, big and fabulicious, the S6Rui delivers a visceral, meaty bass that fills the room.

The bass will not be fat-shamed, not today. Ever the attention grabber, it turns heads figuratively and literally, with physicality that will surprise you. The sub-bass rumble reaches for the throat, while the midbass punch and authority are worthy of a dynamic driver.

The bottom-end extension is nigh-on impressive, as are the dynamics, impact and slam. If this sounds like a wrestling match maybe it is. If you’ve ever come away disappointed with an expensive monitor with a polite bass, have I got good news for you. The S6Rui plays extremely well with modern genres, with a genuinely exciting bass that sets pulses racing.

Full Bloom

Notes are lush, thick and full-bodied, with a sharp, on-point attack or lead-in followed by a warm, well-rounded bloom. While it scores full points for getting the basics right, it loses slightly in the technical departments. Bass speed, detail, layering and resolution are found wanting, while the repeated, unadulterated onslaught might lead to bass headaches. Consider yourself warned, but the S6Rui bass is truly pleasing to the basshead’s ears.

Not that I condone alcohol, but I do love them sweet miniature thrones for my IEMs to sit on.
Not that I condone alcohol, but I do love them sweet miniature thrones for my IEMs to sit on.


Ask any teenager what they’d like to be when they grow up, a whole lot of them might say they want to be rich and famous. As I grow older and fame and wealth seems like far-fetched exercises in futility, I see the beauty and simplicity of leading a life of utter normalcy. Driving the kids to school, office job, dinner at home, yeah, love every bit of it.

Joy of the Mundane

The S6Rui’s mids embrace the ordinary. No shame in treading a road oft-travelled so long as it’s sane and sensible. Located a step back from the aggressive bass and shrill treble, the mids keeps the signature grounded. It’s luscious and full-bodied, with the lower mids giving weight and grunt to male vocals, staying even throughout, and rising in the upper mids to give due prominence to female vocals.

The mids are tightrope-balanced. Unlike the overindulgent bass, instruments and vocals are well-separated and layered, even slightly airy. The timbre, while not an emotionally impactful tear-jerker, is pleasing and pleasant. Transients are smooth and notes flow naturally into one another. Technical ability marries tonal accuracy. While the mids don’t do anything exceptionally well, it’s difficult to find fault in them here.

For the record, I don't know what Rui means. My only lead is a Portuguese footballer.
For the record, I don’t know what Rui means. My only lead is a Portuguese footballer.


Like a roller-coaster, the S6Rui treble teases and excites. The upper mids ascent continues to a lower treble peak, laying bare a ridiculously high level of detail. Notes are sharp and precise in attack, with a good amount of body but lesser in comparison to the mids and bass. Here, the most air resides throughout the signature, and it’s crispy and cool.

There’s an ample amount of sparkle and shimmer to guide lost souls to the path of treble enlightenment.

The S6Rui delivers excitement in spades, right up to mid-treble. Cymbals crash and decay naturally without sounding tinny. Most of the notes round off with a smooth finish as well, so the treble straddles the thin line of being engaging enough without sounding harsh or strident.

Cloudy Skies

Going past mid-treble though, the extension takes a sudden fall, like the steep descent of the roller-coaster. All good things come to an end, and the upper treble collapse means the entire signature is bereft of some valuable air and resolution. While S6Rui does a wonderful job given its limitations, we are left wondering what might have been with just a little more air and transparency up top.

Being transparent means you can blend into the background easily on a particularly antisocial day.
Being transparent means you can blend into the background easily on a particularly antisocial day.

Soundstage and imaging

Pride comes before a fall, and S6Rui’s stage size is astoundingly, breathtakingly… small. In the pursuit of the ultimate sound signature, they are unfortunately caught being sloppy and tardy in the soundstage department. The forward and aggressive, even fearless presentation, if you will, reduces the stage size to tiny proportions, with most of the sounds inside or orbiting the head.

Too Close for Comfort

Of course, some would argue this contributes to full immersion of the music, like getting your head dunked in water when all you want is a swim. The small stage itself wouldn’t be a problem if it wasn’t for the bold, thick notes of the signature. This easily leads to congestion and imaging haziness.

You can discern instruments and voices in all three axes, so it’s not an outright failure. But when you want to make sense of all 20 layers of a complex Tool track, for example, that is something beyond the capabilities of the S6Rui. Like wrapping your head in saran wrap, S6Rui’s over-intimate stage and imaging will turn off some and scare others.

Doesn't work as salad topping, sadly.
Doesn’t work as salad topping, sadly.


FiiO FH5

Meet the standard. The FH5 has been my go-to in the $300 category since its release because it does so many things correct.

Starting from down-low, S6Rui’s boisterous bass proves nearly a match for the dynamic-driver (DD) FH5, delivering superb rumble and punch but just lacking a bit of control. FH5 comes away sounding more natural, especially in note decay, but less fun compared to the loose, dirty, and frankly promiscuous S6Rui bass.

Dent in the Armor

FH5’s most apparent weakness is the lower mids dip, which makes male vocals ring hollow, well guess what. S6Rui smells blood and rains forth its fury, attacking the FH5 where it hurts most. S6Rui effortlessly provides a richer, more satisfying lower mids experience, like a filled donut.

The FH5 redeems itself by sounding considerably better from the middle mids upwards. Here the FH5 is more realistic-sounding, while S6Rui is crisper and airier but with harder edges. There is a slight echo effect in S6Rui’s rendering of vocals, giving an airier but more distant presentation. While not obvious at first, FH5 has better timbre and tone, while S6Rui has more excitement.


As for the treble, S6Rui is aggressive and resolves more apparent detail. It sparkles brighter and more daringly than the FH5, who chooses a more serene, sedate, and smoother path. The treble might be more of a preference game, but it’s game over for S6Rui in the soundstage department. FH5 has simply a more spacious and better-differentiated stage, while S6Rui’s in-your-face approach hurts it immensely.

Overall, S6Rui is the better technical performer, with a coherent tuning that surpasses the FH5, but is hampered by its poor soundstage performance. If you value a great tuning and care not about stage dimensions, S6Rui should be high up on your list.

A right mess of entanglements.
A right mess of entanglements.

FiiO FA7

If S6Rui followed the V-shaped tuning template to great effect, FiiO’s FA7 can be seen in another tried-and-tested, cookie-cutter tuning philosophy, the warm and smooth signature. Lush, coloured, velvety and relaxed, the FA7 is the warm monger among IEMs.

S6Rui’s fun-first, face-first demeanour does translate to better extension both ends, with sub-bass and treble more palpable and easily heard. FA7 devotes most of its attention to upper bass and mids, hoping to seduce you with syrupy sweet, warm notes where technical ability falters. It does work in some ways. The FA7 has arresting mids and a marvelous timbre, leading the way with slow-tempo tracks.


If intimate, well-tuned mids decided things, FA7 would already be halfway home. However, same as how soundstage and imaging performance is the fatal flaw of the S6Rui, FA7’s deal-breaker is the midbass bleed, nearly spoiling the mids. As unwelcome as your little brother tagging along on a date, the midbass bloat threatens to undo all the beautiful imagery left by the mids, leaving a fat mess.

So the S6Rui emerges triumphant in tuning, coherency, and technical brilliance. You can hear where all the extra dollars went to. The FA7 might have better mids and soundstage capability, but is too much of a genre specialist to really recommend over the S6Rui. The Fearless IEM is built to handle much more varied musical tastes, while the FA7 can only look on jealously.

Naked and nowhere to go.
Naked and nowhere to go.

Final Words

The world of Chifi works like a beauty pageant. You have your day out in the sun, dressed to the nines, but only a moment to dazzle the audience. Bass, mids and treble are judged like national costume, swimsuit and evening gown. Capture their hearts and hope to bask in the limelight a little longer, before the next batch of contestants come in. It’s a cutthroat industry, so try to imagine some kittens as you read.

Kittens With Attitude

Mention the name Fearless Audio though, and chances are you’ve heard that they’ve done more right than wrong, with a few standout products that might just win pageants. Here, the S6Rui sashays on the catwalk with swagger and sure-footedness that belies its newcomer status. It’s one of the finest V-shaped tunings I’ve heard in recent memory, and puts me in a toe-tapping mood almost instantly.

At a time when companies are toying with piezo-electric tweeters or electrostatics, S6Rui keeps things simple. No gimmicks, no angles, just BAs in a shell and a competent tuning. This bodes well for the long term growth of Fearless Audio. Sure, they have their weird experiments, and have just unleashed a new wave of hybrids. But even if they crash and burn, they have the basics to fall back on, which might turn out to be their greatest strength.

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