Fearless Audio S6Rui

Johnny Mac

New Head-Fier
Pros: Solid UIEM build, clean midrange performance, easy to ears sounding highs.
Cons: Loose 2pin connection, loose round braid in the cable, lack of lip nozzle.
It’s an upfront name – or really just another attempt of translating a set of ideals into a word that associates itself with taking a leap, charging head on with little regard to either the gains or the losses. A high risk attempt will also incur either high losses or gains. I haven’t heard of the Fearless Audio brand before within the circle of audiophile communities that I’ve been following so it was a surprise when they came barging in releasing a slew of IEMs, or so I thought. Fearless Audio has been doing most of their wallet damaging moves in China and only decided to move out and see what the whole world has to offer or what they can offer. You can check out their full on Fearless Audio Chinese website if you want to dig deeper.

What we have now to realview is the Fearless Audio S6 RUI, their median rendition of how they interpret a $400 IEM, more or less. Linsoul Audio sent the S6 RUI in exchange for an honest take on it, there were no monetary factors involved as well. The Fearless Audio S6 RUI currently retails at $389 for its UIEM version with the transparent series design. A multitude of customization options can be used on the S6 RUI, from making it into a CIEM along with your own choice of faceplate design and shell color choice which could run up to $505. You can check out the revamped and redesigned Linsoul Audio webpage to check out the S6 RUI as well as the whole Fearless Audio lineup.
The Fearless Audio S6 RUI features 6 Balanced Armatures (1 Sonion Dual Bass BA Driver, 1 Knowles and 1 Sonion Midrange Frequency BA Driver and 2 Knowles Treble BA Driver) with 3-way crossover and 2 sound tubes. It is spec’d out with a 20Hz to 20kHz Frequency Response, 113dB/MW Sensitivity, 26dB Passive Noise Reduction and 20 Ohm Impedance. The S6 RUI surely feels like it would be a great-sounding IEM from a relatively new brand and we would be here to see it unfold, for better or for worse. Let’s get this on!

Packaging and Build Quality
The Fearless Audio S6 RUI came in a clean looking cardboard board box which doesn’t show anything on the front except for an outline of a UIEM along with the Fearless Audio logo and branding on the lower left corner and a QR code and product specifications at the back. Inside will reveal the black horizontal hard case and metal ownership card indicating the serial number, maker, date manufactured and factory address. The accessory set of the S6 RUI is a total overkill especially with the ear tips, along with a cable clip and cleaning tool. Here’s a list for the included ear tips:
  • 1 pair gray foam ear tips
  • 1 pair blue foam ear tips
  • 1 pair red foam ear tips
  • 1 pair black foam ear tips
  • 3 pairs whirlwind ear tips (S, M and L)
  • 3 pairs black silicon ear tips (S, M and L)



The Fearless Audio S6 RUI may come in any design depending on the users’ preference but what the common factor would be is that they would all come with a smooth finish and no imperfections as well as bubbles and nicks on its faceplate and shell. The nozzle highlights the 2 sound bores along with the lack of nozzle lip which made tip rolling for the S6 RUI annoying and will oftentimes leave most of the ear tips that I used with it despite the already overkill inclusion of ear tips it comes with. The 2-pin socket is a bit recessed as well and I’m not sure if it’s possible to request a flushed one, Linsoul Audio is very much responsive to queries so feel free to verify if that’s the configuration you’d want. The overall comfort for the S6 RUI’s UIEM version was great and rests well on my ears, isolation is once again top-notch thanks to the UIEM silhouette.


The stock cable that the S6 RUI comes with an 8-core SPC cable which terminates into a 3.5mm plug. The cable is covered in silver and TPU and uses metallic silver hard plastic Y-split and chin slider with the Fearless Audio logo and branding. The cable uses round braids which is loosely assembled attributing to very soft feel of the cable which is even shows flabby portions within the braids. The 2-pin .78mm plug is housed in a metallic silver housing with red and blue line markers as well as an over ear memory wire guide. The 2-pin plugs when plugged into the S6 RUI feels loose and needs only a minor tug for it to detach which isn’t great at all. I tried using the stock cable on other .78mm IEMs and it worked great as well as using different 2-pin .78mm cables on the S6 RUI which also worked great, so it’s just a case of an imperfect match between the S6 RUI and its stock cable. It won’t fall off easily though if that’s what you are worried about. There is also minimal microphonic noise to be observed when using the stock cable on the go.

Fearless Audio opted to release 2 variations for the S6 namely the Rui and the Pro. The S6 Rui is marketed to have a sound with a slight focus on the upper frequency performance. I, myself loves a well-defined upper frequency performance so the S6 Rui tickled my curiosity right when it arrived. I used the stock Medium whirlwind ear tips for the duration of the realview despite it falling victim to the S6 Rui’s lack of a lip nozzle thus resulting in numerous times that the ear tips got stuck on my ears once the S6 RUI is removed. The S6 Rui overall sounded balanced with good coherence between the low-end and the midrange tones and a soft emphasis on the highs which we would get into detail. I used the Sony A46HN music player as well as the Sony CAS-1 desktop system off the MSI GF62-8RE laptop via Foobar2000 v1.4 outputting various FLAC files which would be mentioned along the realview.

The Fearless Audio S6 Rui is able to give out a low-end performance that would keep you glued to your seat, bass drops are impactful and thumpy. I used Lady Gaga’s Brown Eyes track in 24/44 and while it isn’t fast and nimble, it is still able to deliver a punchy and thick sub bass rumble. The mid bass is weighty and tight, one that accompanies subsequent bass drops to showcase a full-bodied bass delivery. The Fearless Audio S6 Rui is far from being a basshead IEM but the way it handles the low-end cleanly is notable and it’s good that Fearless Audio can achieve this and not overdo just to gain a following.

While the low-end performance of the S6 Rui hints at a careful control of not overdoing, the midrange performance of the S6 Rui exemplifies a soft and oftentimes tested approach by making sure that it sounds clear and detailed. Norah Jones’ Nightingale track in 24/88 FLAC was rendered articulate and smooth. The lower midrange showed great coherence with the overall midrange tonality by giving a full-bodied presentation but is near being distant-sounding. The upper midrange is controlled well with a hint of being slightly-boosted. The S6 Rui is a good companion for those midrange-centric IEM lovers.

This is where the gravity is at, the center of attention. The S6 Rui is supposed to be the high frequency performer that Fearless Audio envisions for its S Series of IEMs and there is truth to it, not set in stone but it indeed exhibits an elevated high frequency performance. I used Foster the Peoples’ Doing it for the Money in 16/44 FLAC to test out the highs and it was able to deliver a raspy and crisp treble that is still able to transition into a mellow pace for an eventual open and sweet experience. There is sparkle to be observed as well. While the upper frequency on the S6 Rui is evident, the fatiguing experience is nowhere to be found and so is sibilance. This might not give that wicked treble bite that some craves but at least the S6 Rui doesn’t shy on being bright sounding at times.

Soundstage and Imaging
The Fearless Audio S6 Rui has a depth focused soundstage presentation. It is able to give out a precise imaging experience as well. Instrumental tones and placement are easily discernible. While there is ample left to right and right to left panning to be observed on the S6 Rui, it doesn’t reach a wide sounding ambience. Layering is great and accurate thanks to great detail retrieval performance of the S6 Rui. I wouldn’t be using the S6 Rui for my gaming sessions.

The Fearless Audio S6 Rui tries to do multiple things at a time and while it does some parts exceedingly well like juggling the high frequency gamble of offering treble extension while not being harsh-sounding and hitting just the right amount of midrange body is already enough to make it an already easy to enjoy IEM. It suffers a crucial hit on some areas like the lack of a lip nozzle and the rather loose braiding used on the already fantastic looking cable which continues to its 2pin connection. The accessory set is great and would appease the lip nozzle issue a bit as well as the cable clip. I just hope they do away with the excess ear tips and cable clip and address the weaknesses, as the name says, Fearless.


Reviewer at Headphonesty
Pros: 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
Cons: 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
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.

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?

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.

This review was first featured in Headphonesty.

Equipment Used:

  • Sony NW-WM1A “K” Modded, FW 2.0
  • Amber Rubarth – Scribbled Folk Symphonies
  • Bon Jovi – Cross Road
  • Ed Sheeran – Divide
  • Fleetwood Mac – Tango In The Night
  • Linkin Park – One More Light
  • Meiko – Playing Favorites
  • Pet Shop Boys – PopArt
  • Prince – The Gold Experience
  • Take That – The Circus
  • The Eagles – Hell Freezes Over


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.

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.

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.

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.


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.

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.


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.

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.


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.

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.

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.

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.


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.

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.

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.

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.

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.


Headphoneus Supremus
Pros: An affordable entry into balanced armature perfection
Cons: Nozzle ends don’t always hold tips on when removing S6Rui from your ear
Fearless S6Rui IEM Review


Fearless S6Rui Conclusion: Let's begin this review at the end!

While the S6Rui doesn’t go the lowest, nor sparkle with the highest treble response in all of IEM land........... it all works out?

It’s soundstage is not the widest nor thickest, but somehow it’s the prefect tone, walking that fine-line between musicality and detail, flatness and excitement.

To quote a 1970’s audiophile magazine..........”This is a piece of audio equipment you plan on listening to for 20 minutes, but end up liking for 3 hours straight.”


All of the Rui’s quality may not be fully noted on first listen as the playback is actually very reserved......still the tone improves in brightness of color and clarity by the day? Why this phenomenon takes place, I’m without words? PM me if you know?

If these are not perfect reasons to recommend an IEM, I don’t know what is? I’m strangely enamored by the buttery smoothness and spot-on detail. It’s a slightly warm IEM, yet maybe warmer in the areas you want. It’s the easy-going treble that just makes it so listenable for long periods. And while I own other more expensive IEMs which offer harder hitting technicality; I sit here writing what I’m writing and believing what I believe? Go figure?

Listening to the Fearless S6Rui in person is confirmation of it’s current popularity in our community. Fearless offers both an upper-line and a down-line with the Rui siting smack-dab in the middle.

It’s not that the Rui is the greatest at anything but wins out by not being terribly bad at anything either. Then there is the price......lol. The fact that now in 2019........Chi-Fi mid-Fi has now approached USA flagship territory! With value like this.........domestic manufacturers must be shaking in their boots?

This level of playback was not even dreamed about costing $389....24 short months ago. And.............it seems this Chinese value trajectory hasn’t even started to apex? The only solid reason I can give out as to why not to buy the Rui...................is what is possibly coming again in 24 more short months. Still in my collection it sits in a special place, not due to it’s value but because at any price..........it’s a true contemporary classic.


I’m not mentioning names but if your reading this review I’m sure you know of $800 flagship IEMs from just a few short years back which are fully bettered by this product on all levels. So is progress I guess?

Most of the time the reviews of my favorite IEMs don’t suggest a blind purchase, but here I would think many would simply enjoy such a jack-of-all-trades IEM? There’s nothing not to like here........and I’m pretty sure at this place in time the Fearless Rui owns the $400 market. Still I haven’t heard everything and there is a good chance spending $500 or more on another 2019 IEM could produce even more happiness?

The S6Rui Included Cable:
Normally I don’t write much about the included cables with IEMs. At best they are a fringe subject, with half the listeners feeling they don’t do much to alter sound, and the cable enthusiasts already having an upgrade cable ready to put into use. Though here it seems the cable is special. I ended up trying it out on a number of 2-pin IEMs and seem to notice an improvement in separation and imaging. It’s also the same cable you get with Fearless up-line purchases. Though Fearless also offers an upgrade 2-pin cable if your so inclined.

For those only interested in cable build and ergonomics; all is well. Great cable dexterity and no cable noise transfer. The chrome straight plug is not only matching but of great quality. A trendy-big-aluminum-splitter and slider included, normally found with pricy aftermarket purchases. Strangely I have come to really appreciate the included S6Rui cable and will pursue a 4.4mm variant. The included cable seems to have clearer bass definition than my $136 HanSound Zen 4 Wire? Very strange to say the least?


S6Rui VS Sony N3 Price $338 USD
S6Rui VS Sony XBA Z5 Price $400 USD
S6Rui VS Sony IER-Z1R Price $2000 USD
S6Rui VS BGVP DM6 $199 USD
S6Rui VS Noble Audio K10 Encore $1850 USD
S6Rui VS Magaosi K5 $199 USD
S6Rui VS BQEYZ BQ3 $68.99 USD
S6Rui VS qdc Anole V3 $549 USD

S6Rui VS Sony N3
Interestingly these two are priced very close if ordering the Sony N3 with the Pentaconn 4.4mm 5-pole plug cable. The biggest and most noticeable difference takes place due to the N3 bass presentation. DD is always going to reach a better dynamic presence (if that’s your thang) and here the N3 bass is also immensely in-action......always. The S6Rui is both controversial and questionable to win-out over the legendary N3......but it does! And even though I’m a diehard fan of the new Sony House Tune, the midrange S6Rui harmonic complexities and detail take the S6Rui to a more preferred place. There is simply more going on.

S6Rui VS Sony XBA-Z5
Right off it’s noticeable how the Rui sounds better right out of a phone. It seems the Z5 is noticeably power hungry; and while the Z5 can easily scale ahead of the S6Rui with a powerful desktop system, it’s much a parallel to the N3 where the Z5 bass creates a slower murky experience. Even if your a bass head, there is no denying the S6Rui is faster and more detailed in bass, mids and treble. Still with the electronic music genre, and properly amped, the Z5 takes the lead here. Due to recent 2019 pricing the Sony XBA-Z5 also sells for around $400 on Amazon.com. In ending it should be noted that in every case the S6Rui is way-way more comfortable to wear and stays perfectly in place, with the Sony Z5 being a fit-failure like a USB stick stuck into your ear.

S6Rui VS Sony IER-Z1R
First off the Z1R is 5X the cost, so..............that’s a big thing to take into consideration. Still a comparison here is relevant due to trying to locate and value the S6Rui weaknesses. The IER-Z1R does have fit issues with a small percentage of the population where the S6 has way less fit problems in reputation. In sound signature it’s safe to say they are polar opposites. The Z1R broadcasts it’s sub-bass to a place only dreamed of by the Rui. Where the Rui excellence comes from it’s lower midrange foundation rolling off slightly on any sub-bass. Our Z1R treble extends far out above the Rui, offering a treble technicality just not possible for the Rui. And of course the Rui is all about the exciting midrange; where the Z1R has mids left out, only at the bottom of the list in importance. Obviously the Z1R is a better IEM, still there is room to own and appreciate the Rui; if anything simply for it’s true complementary experience offered. The Z1R epic soundstage is maybe the first big contrast.........showing not only what a giant soundstage is.....but doing it in a tighter more image-isolated-way. The Sony Z1R offers a more coherent and cohesive phase accuracy, making an overall clearer picture; as expected..........but you already knew that.


When I first heard the Fearless S6Rui IEM I thought of the BGVP DM6; which makes sense as both are Chi-Fi multi-BA IEMs.

Fearless S6Rui 6 balanced armatures
BGVP DM6 5 balanced armatures

Though right from that early stage my idea and impressions started to diverge to the point of considering them opposites? Let me explain why............

The treble is considerably more rolled off on the S6.........failing to reach the intensity of the DM6. Though surprisingly the S6 comes off more refined, warmer and MORE detailed in the treble.

In contrast the S6Rui offers expanded midrange harmonics. A midrange the DM6 wished it had! It’s in the mids where a unique brand of sonic holography takes place?

TheS6Rui bass is slightly less pronounced than the DM6 somehow enhancing our more mid-area perspective? So it’s simple......both IEMs display a subtle V signature with the Fearless S6Rui being way more subtle.

While I’m a borderline bass head, I find warmer (mid-reduced) signatures to be my cup of tea. Due to BA bass always being slightly less intense than DD (dynamic driver) bass, we are met with both a faster decay and a slight roll-off affecting sub-bass. Still with the above taken into account the slight lower midrange boost and overall S6Rui warmth starts tugging on my heart-strings. I have to say the overall tone is just about perfect to my ears. The end result is musicality and listenability. Is the difference of $190 more for the S6Rui worth it? Absolutely a big YES! This isn’t a question of preference, the S6Rui technical savvy wins out on all accounts! Is an additional jump to the Fearless S8 Freedom worth the jump instead? I don’t know; I have not heard it?



S6Rui VS Noble K10 Encore
On pretty much all levels the K10 Encore wins out. Both the Z1R and $1850 Encore are perfect to show what a larger soundstage sounds like in comparison to the S6Rui. Encore imaging is both more delineated and more clear, treble elements reach out farther and have a special magic. Though there is an endearing warmth with the Rui which still holds detail.........making the Encore become noticeably cold in comparison. The Encore while great has a penchant for hiding bass, then excitingly reintroducing bass. While the Rui does not go as low, it's more generous with lower midrange and ample on a style of lovable smoothness the Encore lacks. For my taste there is a section of Rui tone which shows how the Encore is incomplete; this area of interest is in the lower midrange/bass.........which the S6Rui effortlessly does better on all music genres.

Both the K10 Encore and IER-Z1R share the “top-dog” place in my personal collection. They are equally great though very different in what they do. In many ways the Fearless S6Rui comes off closest to meeting the K-10 Encore sound as they are both pure BA IEMs.

But this is where it all gets interesting. The K10 Encore shows an incredible and spacious treble expansion offering imaging way-way out in the soundstage showing the limits and holdbacks offered with our $389 S6Rui. Still where the Noble is slightly more detailed and slightly “brighter” the S6Rui still maintains a confidence and composure.

Ok........so this is where the fun begins. Both the Noble K-10 Encore and S6Rui are incredibly well rounded performers. Both IEMs do all genres of music. Though for me the big difference comes with the lower midrange personality of the S6Rui. This “big” “luscious” and “fluid” lower-midrange is nothing short of an IEM enthusiast’s dream. While both the IER-Z1R and Encore go a little deeper, offering a sub-bass experience; the Rui ends up showing off this exotic lower midrange and bass which is both fluid (saying it twice) and warm. It’s simply different than what the flagships do and unexpectedly lovable!

Describe It........
To describe the S6Rui...........when your fully on-board the boat, you don’t necessarily care about the missing technicalities of a four-figure flagship. There is just a complete picture where the S6 does it all, has detail, and this huge expanded and detailed midrange; upper-midrange AND lower midrange and bass which is fully natural and glued together. It's probably positioning in the imaging which pulls this all off? It’s that separation that has folks using the stupid word holographic! It’s just a nice balance of detail, tone and imaging which has you coming back.

Why Would Someone Want The Fearless S6Rui?
Here Head-Fi there is an ample amount of concern on correctness and ability. Somehow at the top of IEM judgment there is no room for error. In many ways these value laws end-up way too critical. Does someone only stay in one room of their house? Of course not. The S6Rui offers an enjoyable middle-ground which ends up being a value to someone with summit-fi flagships. The S6Rui is also competent enough to be all many would ever need as the flagship in their collection. It’s this accurate and accessible right-near flagship level ability which makes the S6Rui such a needed commodity today. Again it’s the fact that it does so much wonderfully right and very little wrong. As talked about there are more expensive IEMs offering more spacious treble soundstage experiences. There are many IEMs offering a dB or two of extra bottom. But at the end of the day there is such a well done distraction going on you forget about any critical judgements.


S6Rui VS Magaosi K5

Priced at $199 the Magaosi uses 5 balanced armatures but seems to end up low-end shy by all accounts. While this style of replay gets attention by a select few who admire and gel with such a tone; I can’t help but look at the S6Rui as an advancement; having a more enjoyable and complete character?


Priced around $68.99 the BQ3 has the reputation as the 5 driver per side bass-centric hybrid phenomenon. Imagine a heavy bass signature but due to dynamic driver authority even more bass. In fact a pair of BQ3 IEMs share two dynamic bass drivers per side. While good in their own special way, here is a great example of more midrange being better.

S6Rui VS qdc Anole V3

Both IEMs are Chi-Fi pure balanced armature IEMs; but that’s where the similarities stop. Take the heavy bass response of the BQ3 and closely emulate it with balanced armatures and you get to the qdc Anole V3 sound. Though again as with much of the comparisons here, the Fearless S6Rui midrange and overall special (close to perfect) balance helps separate the two IEMs in the end..........driving an emotional-wedge between me and my love for the qdc Anole V3! Sadly I have to admit the S6Rui wins again, even over a higher priced IEM.

My Reviewing Process:

Typically after a 50 to 100 hour burn-in process I just listen to the IEM on a Sony WM1A and WM1Z. I then switch to a desktop amp or two and an IPod or phone. As I start to get ideas I will do side by side comparisons then put the review IEM away for a week. At this half-way mark I make notes with impressions. After a week of listening to other gear, I bring out the review IEM and test it again against my initial impressions. At this point I feel my ideas and concepts are ready for an accurate review. Linsoul mailed me this IEM free of cost for review purposes, it does not have to go back home.


Technic Features: 6 BA Drivers , 3-way Crossover, 2 Sound Tubes

Drivers: Micro Knowles Balanced Armature Driver, Including Sonion Dual Bass BA Driver*1, Knowles Mid-Frequency BA Driver*1 and Knowles Treble BA Driver*2

Sensitivity : 113dB/mW

Impedance: 20 Ω

Frequency Response: 15HZ-20KHZ

Features & details

  • 6 Balanced Armatures Earphones. The Fearless Audio S6 Rui has 6 balanced armatures with 3 way crossover tech and 2 sound tubes. It has 6 Micro Knowles Balanced Armature Driver, Including 1 Sonion Dual Bass BA Driver, 1 Knowles Mid-Frequency BA Driver and 2 Knowles Treble BA Driver. It can perfectly present wide sound field, high resolution sound quality. It also excels in high frequency with better elasticity
  • Unique DDP Technology. As a brand pursuing for perfectionism, we adopts DPP partition pressure treatment technology which can better balance the comfortability and functionality. It offers better wearing experience than traditional earphones
  • Detachable 2Pin Cable. Each earphones come with a detachable 0.78mm 2 Pin cable. With this cable, it also ensures fully upgradability for more choice. You can change it for any other cables you prefer
  • Digitization Mold Tech. As a customized earphone, we can also accept personal ear files. Obj, stl files are accepted.

It should be noted the Fearless S6 comes in two flavors.

  1. Fearless S6 Pro
  2. Fearless S6 Rui

Both models follow the Harman Target in tuning with slightly more treble and bass offered with the Rui. Thus with this tweek the Rui may in some cases come off as having more detail. Just like the name suggests the Pro model would be chosen for a response closer to reality, with the Rui offering a slight enhancement. This description of the Rui should in no way give the impression of finding the Rui response as that far off the Harman Target approaching “fun” territory. But rather the company is offering a slight adjustment arriving at two signatures which will be endearing to two different groups of audiophiles.

Standard Price is $389.00 USD

$25 to $60 extra can be spent on changes from standard, including a full CIEM order if wanted.

Key with additional custom add-one.
Transparent series:K1- K12

Custom Faceplate :

Type A: A1-B7 is USD25

Type B: F6-F7 is USD30

Type C: C1-E5 is USD35

Type D: F1-F5,E6-E7 is USD50

Custom Fit : USD60 (Accept physical ear impressions or digital ear impressions files)

This is some subjective ideas about an IEM...your results may vary from mine.

Equipment Used:
Sony 1Z Walkman 4.4mm balanced and 3.5mm output.
Sony 1A Walkman 4.4mm balanced and 3.5mm output.
Sony Desktop TAZH1ES DAC/amplifier 4.4mm balanced and 3.5mm output. Sony Walkmans as file-servers with dock.
Schiit Asgard One Desktop Amplification single-ended 1/4” output.
Apple IPod 5th Generation 32GB 3.5mm single ended output
Extra Cable:
HanSound Audio ZEN 4-wire OCC litz copper cable terminated Furutech 4.4mm

Music Used;


Box Presentation:

Interestingly the package is minimal with intense quality concentration on the IEM build and finish itself. Basically after you open the black included velvet lined case, you could care less about anything else. Included is a set of tips, a brush and shirt clip. There were no instructions, though the IEMs come with a laser etched card displaying serial number and build date.



After studying the complete packaging setup it’s quite amazing how well everything goes to protect your purchase.

As a six driver IEM we find a beautiful clear acrylic housing absolutely smoothed out to the hilt. Inset 2 pin recession accompanies a fully mounted 3.5mm cable. As noted there is very little nomenclature until you look deeply into the inside of the IEM upon the balanced armatures themselves which charmingly hold name plates etched with both “Fearless” and the name “S6Rui”. It’s at this apex of the box opening process that you fully realize the effort was singularly put into the IEMs. Then upon hearing the S6Rui you realize the quality is real.




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@Redcarmoose, what a fantastic review, the comparison set at the very beginning is priceless.
Have been considering Sony N3 as an addition to my small IEM collection, and now I am having second thoughts after reading your comparison.
Chapeau to you.


500+ Head-Fier
Pros: Impressive bass, good smooth tonality, build and material quality, beautiful case, stock cable,
Cons: Sound may not fit for everyone,
Before starting this review, I would like to share technical aspects and package details.

Also, I would like to thanks to Penon Audio for this great opportunity. Here is the link of the S6 Rui;




Driver: 6 balanced armature (1 Sonion compound low frequency, 1 Sonion compound middle frequency,2 Knowles independent high frequency)

Impedance: 20 ohm

Sensitivity: 116dB/MW

Passive noise reduction: 26dB

Frequency response range: 20Hz-20kHz

Connector:2pin 0.78mm



Package Details:

Fearless S6RUI earphone

Eartips 4 Foam, 3 (SML) SpinFits and 3(SML) Black silicone.

Leather Carrying Case

2-pin SPC 8 Core cable

Shirt clip

Cleaning tool

Metal plaque with information pertaining to the model


Test Equipment:

Lotoo Paw Gold

Astell & Kern AK120

Opus #1


Package, Design & Isolation;

I think Fearless Audio has changed their package design recently. Old package was simple yellow box but now, S6 Rui comes with white designed cartoon box. Inside the box, there are leather cover case, tips, warranty card, and cleaning tools. The carrying case is really fantastic. It reminds me the Anole VX leather case both as design and color. Case has nice touch and its size is pretty enough to keep S6 Rui inside of the box. This is pretty impressive because most of the earphones come with simple carrying case at this price range. It is nice to see that Fearless Audio improves their products and package quality day by day. Cable is another great thing of S6 Rui. Its stock cable is really great and I don’t think I will upgrade it.

My S6 Rui has K9 faceplate with translucent A5 shell design, but there are many other customization options for it, and you can select different designs. And also, you can make your own design as well. This is my second Fearless Audio product and I’m familiar with its shell design and quality. Earphone itself has ergonomic shape which provides good fit and isolation. Built quality is fantastic. No blemish, quality defect or QC issue on it. Like other Fearless products, it has also industry standard 0.78mm 2 pin socket so you can use aftermarket cables with S6 Rui. Isolation is great, no complaint here. I got pretty good seal with the silicon tips. S6 Rui’s body design makes a great comfort and isolation in ears.



S6 Rui is pretty well known iem in the audio community and I guess almost every person who buys it loves at the very first sight. Its sound like a dynamic driver, it has nice energy with dynamism and also provides nice detail in every frequency. S6 Rui is some of few earphones that I heard like this kind of bass performance. It is pretty impressive for a balanced armature driver; it hits hard and sub bass goes pretty deep. Mid frequencies are laid back but vocal sound is slightly forward. High frequencies have nice sparkle and extension and it’s prominent on the overall sound.



The upper frequencies are slightly bright, airy and well-extended. A tremendous feature is that the trebles do not loose their control too much. In general, the S6 Rui has a V-shape sound structure, so I can say that the trebles are quite prominent. The fact that the prominent presentation does not make it sound perfect or good by itself, but it is important how it is tuned. In general, I like the tonality of the upper frequencies as well as its control. There is no metallization in the treble, and it has a natural presentation. I did lots of tests with my favorite Le Trio Jeoubran album, and treble does a really good job on stringed instruments. The separation of the instruments and the airy presentation on stage are pretty impressive.



Mid frequencies are smooth, easy to listen and overall presentation is soft and does not pressurize the stage in any way. Mids are smooth and its detail and resolution level are quite impressive. It is not shy to give many details in music. Mid frequencies are generally laid back than the other frequencies. Tonality is slightly colored and warm. You feel this coloration especially in the instrument’s sounds, the instruments play a little thick and meaty. In fact, lower mid has a big role in here. Vocals seem to be centered on the stage, and it doesn't seem like you hear it all over the scene. Detail level is good to hear every single detail in the music.



Basses are at top of the area where the S6 Rui is the most successful. Basses are really strong, bulky and they don't have any problems about reaching deep. Another thing that surprised me is the beats of the bass are reminiscent of the dynamic driver. Both hits and tonality are very similar to the dynamic driver. Sub basses can go deep very well. I said it was like a dynamic driver, but let me emphasize that you can't get close to a powerful dynamic driver. I love the sound performance of the armature drives, but I think they are a little weak in generating sub-frequencies. Most armature driver headphones are dry and dull with lower frequencies, of course there are some very well tune earphones out there, they are exception. At S6 Rui, I think I can say that it is included in this class. Not dry, not weak or slow, it is very dynamic and natural beats in this regard. Although the bass is strong, it is extremely fast and controlled. It's not the fastest armature driver I've listened to, but in that sense it's definitely good. Overall the bass performance is quite pleasant to listen to and the prat feeling is quite high.



I can say that the soundstage is wide and deep enough to create room for vocals and instruments. But there is no exception here. It is not the best in its class, but it is better than the average I believe. The instruments and vocals can play from pretty wide area and it is easy to listen. Background is black and clean. It provides clean and clear presentation.



S6 Rui vs Atlantis:

These are two different earphones both as sound characters and technical details. S6 Rui has 6 balanced armature drivers while Atlantis has 4 balanced drivers. Both earphones’ material and built quality are fantastic. S6 Rui’s sound is dynamic and rich, it has nice bass slam with extended trebles. S6 Rui takes its power from the low frequencies and it adds body on the overall sound. Atlantis is slightly warmer and it sounds is reference like. Of course, not exactly reference but its neutral and balanced sound signature bring it closer in that sense. S6 Rui is much more enjoyable earphone. Bass is more powerful and pronounced with S6 Rui. Its bass hits almost like dynamic driver, actually its bass performance is better than some dynamic drivers. Atlantis is less authoritative and when it’s compared to S6 Rui, it feels bass light. Roll off on the bass becomes more apparent. Atlantis bass is tighter and faster, but not a big margin. Mid frequencies are bolder and thicker with S6 Rui while Atlantis has airier and more neutral. Instruments sounds are more realistic on Atlantis. S6 Rui is playing instruments bold and chubby way. Soundstage is wider and airier on Atlantis. S6 Rui has also wide soundstage but Atlantis’ gives better feeling. At the end, both earphones are pretty good for sound but it depends on your preferences. If you are looking for a fun signature, powerful bass with dynamic earphone, go for S6 Rui. Atlantis sound is totally opposite. Neutral, balanced sound makes Atlantis almost reference earphone, and if you are looking for that, go for it. But Atlantis’ price is almost double on S6 Rui.


S6 Rui vs Audiosense T800:

Lately Audiosense T800 is one of my favorite iem under 500$ which its sound is really impressive. It has 8 Knowles drivers per inside and configuration is like; 2 dual drivers for high, 4 mid drivers for mid, and 2 drivers for low frequencies. Both earphones’ material and build quality are top notch, no complaints here. Sound wise, they are sharing some similarities in sound. Both S6 Rui and T800 have extended and sparkling trebles. S6 Rui is little bit more extended and it has more energy than the T800. T800 is more relaxed and smoother without effort. S6 mid frequencies are more laid back and it’s like dominating with low and upper frequencies. T800 mids are more pronounced and more upfront than the S6 Rui. Vocal is also forward on T800. But earphone has nice details and timbre on mids but T800 is just a bit better for my taste. It is more romantic and natural feeling. Bass quantity is similar in quantity but S6 Rui hits a little harder. Soundstage is wider and deeper on T800 but that doesn’t mean S6 Rui is narrower. It is also wide and pretty deep but T800 puts more air and space between instruments.




Fearless is a very fresh company but they already made many amazing earphones, and a lot of people using their iems with pleasure. S6 Rui is one of them, and great iem which deserves its popularity in the community. Dynamic and engaging sound with easy to love tuning make S6 Rui as a all rounder. Its powerful bass performance accompanied with smooth and detail mid and prominent clear treble.

All the body and material quality are fantastic. Stock cable doesn’t need to upgrade, it is already good looking and sounds beautiful as well. Leather carrying case is not a usual thing to see in this price range which is great. Overall if you are looking for balanced armature earphone with warm and detailed sound, S6 Rui is a great option for its price.


Headphoneus Supremus
Pros: A CASE!
Beautiful build.
Very nice cable.
Sound, which is quite enticing.
Good fit and finish.
Warranty/ID card.
An overall very nice sounding IEM.
Cons: Cable may not stay over ear for all.
Some may not like transparency, shiny finish.
Somewhat compressed mids (but holographic).
Not much else, this is a very good unit.
Fearless Audio S6Rui ($389usd).

There was a certain rumble…a rumble of whispers, hushed tones of talk, permutations of sonic bliss, promenading portends of vicissitudes regarding a new presence on the block. That new presence was Fearless. And it was purported to be grand, good and right in the world of portable hifi. Would that were be my luck extraordinaire, I heard of an arrangement heading twixt the middle-west of the States, United. Oh goodness bestowed upon me! How hath I become so lucky? Mine mind made me wait for it was the mallow of competence. Wait I did. Upon arrival, I did shed coverings and listen. And it was grand. But…it must faithfully wait its turn. I did glance ever so slightly towards it as other took stage of center. Catching mine eye, I blushed as the pearlesque shown back. I averted glare too much, lest I become embarrassed and fraught with enchantment. Time would come…time would come…


Linsoul: https://www.linsoul.com/product-page/fearless-audio-s6rui-IEM


Technical Features: 6 BA Drivers, 3-way Crossover, 2 Sound Tubes
Drivers: Micro Knowles Balanced Armature Driver *6, Including Sonion Dual Bass BA Driver*1, Knowles Mid-Frequency BA Driver*1 and Knowles Treble BA Driver*2
Sensitivity : 113dB/mW
Impedance: 20 Ω
Frequency Response: 15HZ-20KHZ


6-driver IEM
Silver-coated 8-strand
Locking case
Shirt clip
Numerous tips foam and silicon
Nice metal ID card/warranty link.


Gear used/compared:

All prices in USD, unless noted otherwise:

Oriolus Finschi ($180)
BGVP DM6 ($199)
TFZ Secret Garden ($199)

Thebit Opus #2
Shanling M5s
XDuoo x10t ii/iFi Pro iDSD

Songs used:

Too bloody many to list all, but you want songs, so there you go:

Coldplay-All I Can think About Is You
Coldplay-A Message
Coldplay-White Shadows
Dona Onete-Sonos de Adolescente
Los Lonely Boys- Heaven (en Espanol)
twenty one pilots-Trees
twenty one pilots-Car Radio
twenty one pilots-Heathens
Damian Marley-Everybody Wants To Be Somebody
Damian Marley-So A Child May Follow
Damian Marley-The Struggle Discontinues
Ziggy Marley-Lighthouse
Ziggy Marely-See Dem Fake Leaders
Mark Knopfler-Laughs And Jokes And Drinks And Smokes
Santana w/ Mana- Corazon Espinado

The new twenty one pilots album, Trench
The new Mark Knopfler album, Down The Road Wherever


So began my time with the Fearless Audio S6Rui S6 Pro. A long name usually reserved for critters of the auto variety in an Italian sense. “Lamborghini Vento Extraordinaire Speciale,” the list goes on. But with that long name, there must be the goods to back the talk up. And as stated above those previous to me have had good things to say about the S6 (henceforth known as that because, well the other is too long…), with sound to match its name. Talk of excellent separation, layering, detail and stage of sound came cruxing through my cranial matter. It was jumbled, but understandable. I did appreciate those with which I stay in contact being honest and representing the S6 well. For to them, the critter was/is grand. And I am here to tell you that if this is the mid-fi offering from Fearless, I am on board for the TOTL. The S6 is quite good, and follow this journey to the end for more details…



Coming is a non-descript tan box, the mood is understated, and earthy. Taking the lid off you are presented with a 64Audio-like case, with everything inside. Instructions, tips, cable, a fairly unique shirt tie and the IEM. That’s it. I like the minimalism here. On some, like Clear Tunes Monitor, the box adds to the overall presentation. On others such as Fearless, they let the beauty of the cable and IEM speak. I do not fault either and appreciate both aspects. And at least the boxes on both are functional and sized appropriately, unlike some of late.

An aluminum “credit card” adorned with the Fearless logo on one side and pertinent information on the other such as website, contact information and serial number, lies at the bottom of the case. The person who constructed the IEM is also listed, a nice touch. With a soft-lined foam adorning the case, the critter stays well protected. Understated elegance.



The S6 is a looker. The marble-pearled-like cover bears the logo and a funny “W,” which I am not sure what it denotes. But, beyond that the IEM is a very pretty unit with which to look. Wrought in silver, the jacks and cable match the IEM. A white-silver cable of 4-braid variety compliments the look nicely. With sturdy jacks as well, the feel is one of not necessarily robustness, but solidity. Quiet strength.

With see-through shells, the innards look quite electric. This look goes to show just how thin the connecting wires are in some IEM’s. With a fairly wide bore nozzle (but no lip), tips did stay on well, including the foam tips with which I spent the majority of time. Striped red or blue 2-pin connectors were a welcome addition as well. No mucking about with this, nope.

A polished silver splitter replete with logo (that W…) adorned the cable, and a slider complete with “Fearless Audio” gives the impression of royalty. Understated royalty. Not garish, but present, nonetheless. It looks good, feels good, and has good presence.



When the S6 first arrived, I was in with another “more fancy” IEM, so I set the S6 onto my Shanling M3s for burn in. I played it first of course, and immediately noted something seemed different. An almost squished-holographic nature was had to the sound. 3D indeed, but a bit like an hour-glass 3D.

So, I did eventually return to the S6Rui, and we had a grand time during the write up. Used at first as a comparison tool for others ahead of it in queue, this alone should speak volumes. The S6 is good. Corazon Espinado comes through vibrant and full. Rumble is indeed present in the right amounts a good sign. The dual-bass Knowles doing their job, without fuss. Carlo’s guitar comes across succinct and crisp. Not TOTL crisp, but as much as one would hope for a mid-fi entry. At the asking of $389, the S6 represents itself very well in this department.

Steely Dan’s Deacon Blues, always known for crisp and precise music, comes across as I remember. Turning the volume up, the vocal presentation is worth the price alone. Sublime support vocals come across as expected. The small orchestral support fills nicely intro the requisite niche. Through the Shanling M5s, the volume goes up (it is a bit hard to drive the S6…a bit), and the same holds. Cymbal crash is tight with fast decay. No lingering or muddying the corresponding tone. I can also sense a rumble, which seems to shake the housing as well. I know this doesn’t actually happen, but it is a nice feeling of envelopment.

The only problem I have is when the sax solo comes on. I had to turn the volume down as it seemed to grate my ears a bit. This could just as easily be my hearing sensitivity (it is) as well. Those sounds, which are more forward and “shouty” tend to be, and while presented properly, do still bother. That does not hinder my enjoyment at all.

The mids do have a sense of compression as mentioned above (and possibly other aspects, I cannot tell exactly), and I cannot say it hinders my experience as that holography of sound compensates well. It is almost like Fearless included an automatic iFi 3D+ switch, which comes on as needed.

Running the S6Rui through my current favorite home set up the XDuoo x10t ii/iFi Pro iDSD combo, gives a very good representation as to how versatile the S6 is. Stevie Ray Vaughan sounds like he and his band are giving a concert in your living room. Just a superb representation without any digital falsity that can happen on some set ups. Moving on to pretty much any Ziggy Marley song and you just sit back like you are on a cool beach in the summer. Conscious Party and Lighthouse separately show the versatility of the S6. The more synthesizer-based former song plays well with that holographic sound, complete with vibrant bass and his voice. A strong representation of the song, with wonderful layering of sound to boot.

Lighthouse is one of my favorite test songs (and just a favorite, period) for it gives the acoustic side a chance to shine. Supported by the synth-keyboard, the guitars simply sparkle. Ziggy’s voice cracks with emotion and I just listen again. A bit more centered in sound, nonetheless there is as much layering here as the other. Definition is better as well. Throw in the complexity of strings and you have the whole gamut. I really appreciate how the S6 represents this song in all of its earnestness. I am part of the music in this pairing. Just wonderful.



Fearless Audio S6Rui ($389) v Oriolus Finschi ($180):

I will openly admit I really like both the S6Rui and the Finschi. For the level presented, they are each quite good. The Finschi presents a solid deep reaching bass-tone with good clarity. This reminds me of when the Pinnacle P1 came out and was lauded for its overall tonality. But here, you can clearly hear the steps forward into a much fuller, more robust sound. I will admit to selling my Pinnacle’s because those highs grated on me. And here is the flaw I find in the Finschi. That wonderous bass can become overbearing on some songs, frowning out the laudable characteristics of vocal presentations while rendering more complicated sections a bit disconnected. Mind you it isn’t bad, but that wonderful bass can get in the way.

By comparison, the S6 has less bass quantity but much better control. And because of that control you do not lose the clarity. So, while the Finschi is quite good, and one of the best for the price in my opinion, the S6 betters it by having the overall control locked in much better.

Fearless Audio S6Rui ($389) v BGVP DM6 ($199):

This is another where you could justify spending on the DM6 and just stop. You would be satisfied, and I am amazed at the availability of quality IEM’s at this price. Where even just two years ago quality at the $50 IEM seemed to set the tone, the audiophile world has moved into the mid-fi range as the defining level. The sub/near-$200 IEM now sets the tone. And as such, you would be hard pressed to better the DM6. Yes, the DM7 is now out (look for @b9scramblers review coming soon), but the DM6 is about as good as it gets. I was flabbergasted at the level of refinement in the DM6, even compared to the Finschi. Clarity rules the roost here, but with less bass quantity. Vocals could be called sublime as opposed to just competent. But they are. You really get into the musician’s head with the DM6, and while good, sometimes you just want to sit back and enjoy rather than be a part of. And here is where the S6 steps ahead. The presentation of that sound is marvelous, and hard for pretty much anything under $200 to best. The DM6 is fabulous for what it does: present a very solid fit-n-finish tied to an extraordinarily solid sound but lacking that impact of the others.

Fearless Audio S6Rui ($389) v TFZ Secret Garden ($199):

Quoting from my Secret Garden review: So, through all of this anticipation, waiting, procrastinating and finally writing what did I find? Well, that the TFZ SG is a pretty decent offering in a very crowded field. Listening to Ziggy’s We Are More as I scribe this summarizes quite well my feelings/findings about the SG. Our ears ring so true, but money don’t make the world a better place. Listening is the definitive way to understand a manufacturers intent, for it is through their product that we garner impressions, desires, wants, needs, and displeasures. Happily, the SG falls into the first set and does a quite decent job at doing it. And interesting take on an IEM worth a listen.

The SG is quite good at the price but has recently been surpassed by the likes of the Oriolus Finschi, the BGVP DMG (and 6 & 7), and the Fearless line. That does not mean it isn’t still good, for it is. Simply that technology is passing by so fast, that what is considered good today, may well be adequate tomorrow. Witness the Pinnacle P1, once lauded as the answer below $200. Now it has been surpassed by three years of technology and innovation. The same holds here with the SG. But in most cases, those companies produce “new innovative” IEM’s to replace the “old” unit. Which is a shame, for the SG is good in its own right and should be considered.

Against the Fearless though, it simply cannot compete. The bass is tighter, the sound is wider, more articulate and overall the S6Rui presents a more pleasing package, especially when you throw in that almost holographic sound. The SG could be considered the cousin who wants to be like the older more successful cousin. And in that regard, it is still quite good. It simply cannot compete here, as one would expect.


A word about sources:

I found the S6Rui to be multi-dimensional with regard to source. Running the S6 through my MBP/Burson Fun set up, that "lack of bass" came through with enticing sound. I did not miss the low end, as the Vivid OpAmp brought into play what could be perceived as missing. With the XDuoo x10t ii/iFi Pro iDSD I achieved the same results, but with better clarity as one might expect what with the transport XDuoo and iFi. It was a superb set up, and one in which I spent the majority of my time. I could REALLY get used to that sound (and did). As for portable, my venerable Shanling M5s has become my go to. I love the Shanling sound and her it came out in full glory. The pair seemed made for each other, and if I had a commute by public transportation, this would be in my regular rotation. Heck it would BE my rotation. So, the S6Rui is indeed multi-dimensional and worked across platforms. Some better but all were good. That cannot be said for some IEM's.


As mentioned in the previous paragraph, technology and innovation(s) change very quickly. Spurred on by the SE Asian market and companies who want a slice of the IEM/portable market you see companies come and go almost weekly. That is a shame, for we rarely have time to slow down and enjoy what we have. Rarely do I get to listen to what I want on the IEM I want, when I want. That said, I do get to sneak in listens as part of the review process. I am not the “most famous,” nor the highest up the food chain. But my queue bubbles over with worthy items and as such I need to choose what competitors will pair well with the item tested. And it is here where the Fearless will fit in. For you see, there is a whole lineup of worthy IEM’s from which to choose. Based upon others verbiage, the lineup is good, very good.

If the $389 S6Rui is any indication of what lies within the lineup, then they will become a mainstay of my comparisons, and for those none-too-often times when I can just sit back and enjoy. That is the place in which the S6 has earned in my corral…worthy of inclusion of both sets of the equation. It is quite enjoyable just to use as I sit back and listen, and that does not happen with many of my IEM’s between the queue, and here is where the S6Rui will sit, as that one to stop and enjoy, so that I may collect my thoughts before moving on to the next review. I enjoy it and will continue to do so.

I thank Lillian from Linsoul Audio and Fearless for sending the S6Rui. It truly is a remarkable little critter, and well worth a look in the sub-$500 IEM market.

Wonderful review :) I adore this earphone. One of my absolute favorites, regardless of price.
Thanks, Thomas! It is quite good.


Reviewer at Twister6
Pros: Value for money
Sound Quality - Best Under $400
Smooth well balanced sound
Exceptional BA bass quality
Fit and Finish
Great looking faceplates and shell customization options
Beautiful looking cable
Cons: None for the price

Nitpicking - Cable could use a better jack
My background- I am a professional musician, producer and audio engineer with experience in the performing, recording and pro-audio industry. I test products on a technical and musical level and try to write reviews as simple as possible from a music fan's perspective.

Disclaimer – This sample was sent to me to test and review. I am not affiliated with the company or the seller in any way and write this review with my unbiased opinion regardless of how the review turns out.

S6RUI Solo.jpg

Fearless S6RUI is available for a base price of $389 at Linsoul - https://www.linsoul.com/product-page/fearless-audio-s6rui-IEM

Reference Songs list-
  1. Foo Fighters- The Pretender, Best of you & Everlong
  2. Coldplay- Paradise, Up in flames & Everglong
  3. Ed Sheeran- Thinking out loud, Bloodstream & Galway Girl
  4. Chainsmokers – Somebody, Sickboy, This Feeling & Closer
  5. John Mayer- Slow dancing in a burning room, Stop this Train & Say
  6. Gavin James- Always & Hearts on fire
  7. Switchfoot- Meant to live & Dare you to move
  8. Linkin Park- Papercut, One step closer & Somewhere I belong
  9. Maroon 5- She will be loved, Payphone & Lost stars
  10. Lifehouse- All in all & Come back down
  11. Karnivool- Simple boy & Goliath
  12. Dead Letter Circus- Real you
  13. I Am Giant- Purple heart, City limits & Transmission
  14. Muse - Panic station
  15. James Bay - Hold back the river
  1. Driver - 6 Balanced Armature
  2. 1 Sonion dual BA for bass, 1 Sonion dual BA for mids ,2 Knowles BAs for highs.
  3. Frequency response range: 20Hz-20kHz
  4. Impedance: 20 ohm
  5. Sensitivity: 113dB/MW
  6. Isolation: 26dB
  7. Cable - 2pin 0.78mm 8 core cable
  8. Plug:3.5mm
Included in the box-
  1. Fearless S6RUI
  2. Eartips – 4 Foam, 3 (SML) SpinFits and 3(SML) Black silicone.
  3. Plastic Carrying Case
  4. 2-pin 8 Core cable
  5. Shirt clip
  6. Cleaning tool
  7. Metal plaque with information pertaining to the model
S6RUI with cable.jpgS6RUI eartips.jpg

Build Quality- S6RUI has good build quality. The shells are 3-D printed and made up of resin. They are crystal clear and you can clearly see the drivers inside which either spot the company’s name ‘Fearless’ or the model number, ‘S6RUI’. The shells do not have any bubbles and the seam between the faceplate and bottom shell is flawless too. The 2-pin sockets are recessed which enables part of plastic before the 2-pins of the cable to go in. The sound bores in the nozzles have been drilled very neatly too.

The 2-pin 8 core cable provided in the package has an attractive silvery white color and feels very well made. It’s not the most flexible cable but it has a very good feel to it and has absolutely no microphonics. There is an odd problem though, it crackles if you twist the jack while it is plugged in. It might be due to the lack of gold plating on the jack and a slight build-up of an oxidation layer, but it doesn’t matter if you’re not a nitpicker like me as it does not alter the sound performance even a bit. Trust me, I’ve compared it with the other cables I have. Impedance of the cable is around 250mΩ.

S6RUI.jpg S6RUI nozzles.jpg

Fit and Comfort- S6RUI has an extremely comfortable fit for me, probably one of the best I’ve tried under $500. I would’ve enjoyed if the nozzles were just a smidgen longer but regardless of that, I get a very snug fit with good isolation. All the curves of the shells are polished well and feel nice around the concha of the ear.

Sound Analysis -

Bass -
If you like bass and have been complaining that balanced armatures can’t play bass all this while, THIS IS YOUR IEM! The S6RUI has good-punchy-impactful bass that I’ve always expected from a dynamic driver. I like it! It has good rumble when required, the sub-bass can go low, mid bass and high bass shines in songs with overdriven bass playing in bands like Karnivool, Muse and the likes.

Let’s dig-in in detail with some songs as reference.
  • Kanivool’s Simple Boy & Goliath – If you’ve been reading my reviews, you know I love these two songs for the bass. The S6RUI nails the overdriven bass sound. It has well present sub-bass, good mid-bass and snappy high bass with good bass string definition.
  • Chainsmokers’ Somebody – If you’ve heard and like this song, I’m sure you would’ve gotten hooked to its falsetto based hook line. But right after the intro, an 808 and an overdriven stereo synth bass makeup most of the instrumentation.
    Both the basses have good impact and separation, keeping their individual identity strong and present throughout the track.

  • Muse’ Panic Station – It starts with a bass slide and off to a snappy groove where the S6RUI makes the bass shine along with the drums. In most BA sets, the drums take the spotlight. But the S6RUI re-creates the gnarly bass tone that Muse is known for with utmost ease and poise.
Mids – The mids have good weight to them. They sound natural, thick while still very smooth with great clarity and separation. I know these adjectives don’t generally go together but well, it is true in the case of S6RUI. The lower mids enable the snares to have good body and meat whereas the high mids help guitars with attack and percussion shells with good stick attack. Instruments have a good timbre and vocals sound authentic and life-like, as if the artist is performing right in front and only for you.
  • Ed Sheeran’s Thinking out loud – Ed’s voice sounds very natural. The strat guitar tone sounds very authentic too. The separation is so good that I can even hear the spring reverb every time he percussively mutes the strings while playing the main chord progression.

  • James Bay’s Hold back the river – The hollow body Epiphone that James uses sounds so natural that I can certainly hear its authenticity. James jumps between his real voice, head voice and falsettos dynamically throughout the song. His vocals are presented very well by S6RUI. All the voices in the falsetto based chorus are identifiable individually. The tambourine also sounds very natural and well present whenever it is played in the song.

Treble- The treble is smooth. It isn’t overly boosted which helps give S6RUI a smooth character and also keeps it fatigue free. But don’t mistake it for being a dark sounding set. Even though the treble is smooth, it still extends decently well and enables S6RUI to have good clarity and definition. Also, there are no rogue 8kHz peaks so you’re not going to hear any added sibilance here.

Soundstage, Imaging and Separation – Soundstage has more than average width, I’d rate the width around 7 out of 10 (where 5 is average). Imaging is precise and well done. Separation, layering and resolution are very good for the price. I guess the drivers are doing their job, playing their parts well.

Comparisons –

S6RUI vs S8 Freedom –
As everyone is extremely interested in this comparison, I hope I can do it justice.

Think of S6RUI as S8F’s sibling who is younger by a year (2 drivers :wink: ). S8F sounds more airy and creates a better sense of space. It has more sparkle and snap in the 2-6kHz region. The mids are thinner and have better resolution. The bass sounds more authentic, tight and cleaner but both S8F and S6RUI have good slam! Personally for me, the S8F sounds more exciting and refined, with better resolution overall.

But on the other hand, S6RUI is warmer of the two and an easier listen. If you don’t want as much resolution and prefer listening to an easier sound signature, go for the S6RUI. But if you want a more detailed and resolving IEM, S8F is the one.

Conclusion – S6RUI is a very impressive IEM from Fearless, who have priced it extremely aggressively. It is one of the cheapest 6 BA driver IEMs which uses all original Knowles and Sonion drivers. It has very good build quality, countless faceplate and customization options but the MVP of this unit is its extremely well-tuned and enjoyable sound signature. If you want a jack of all trades, this is the one to get. Highly recommended!
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I majorly use pro-grade equipment in my studio. Thunderbolt Audio interfaces -Slate Digital VRS8, Universal Audio Apollo and Focusrite Clarett 8PreX. Rupert Neve RNHP headphone amp. I have other multi-out headphone amps too.
Playback for testing- Logic Pro X session with hi-res tracks mentioned above in the review for ease of having them in one place and to check various things like isolating individual dominant frequencies or frequency bands, imaging or as easy as normalising levels accurately using meters for comparisons between different IEMs with different impedances.
Even though it is a bit of overkill, it's all setup and all I need to do is plug in the headphones/IEMs. Also, it is fun and makes all of this more interesting. For casual listening, LG V40 or OnePlus 7 Pro.

PS- Had to break it down to 3 messages 'coz of character limit.


Headphoneus Supremus
Pros: Build - Comfort - Visual Appeal - Refined, entertaining yet mature tune - Sweet cable and accessories
Cons: Right ear piece randomly detaches despite a seemingly snug fit - Bland packaging - Lacking a lip to hold 3rd party tips on

Today we're checking out one of the mid-range models in the Fearless lineup, the S6 Rui.

The last few years have seen Chinese audio manufacturers really take off, and they're not slowing down. With brands like Knowledge Zenith absolutely dominating the budget sector, it was only natural for other markets to see massive growth too. For 150 bucks you can get a feature rich and very impressive sounding earphone that makes you question why you'd ever considering spending the same amount or more on something from a mainstream brand. Fearless Audio, established in 2012, seems to be taking the same approach but with the mid-tier market. For the sub-500 USD price tag the S6 Rui commands, you are getting a whole heap of performance and quality for not a lot of money... to some.

Let's take a closer look at why this earphone should be high up on your list of gear to get in 2019.


Thanks to Lillian with Linsoul Audio for arranging a complimentary sample of the S6 Rui for the purposes of review. All thoughts within are my own opinion based on time listening to the S6 Rui and do not represent Fearless, Linsoul, or any other entity. At the time of writing, the S6 Rui retailed for 389 USD. Note that the S6 Rui can be heavily customized (for an additional fee) so if you're not a fan of the design seen here, you can easily swap to something more your style. Check it out here: https://www.linsoul.com/product-page/fearless-audio-s6rui-IEM


The S6 Rui was paired primarily with my TEAC HA-501 desktop amp with either a ZiShan DSD or HiFi E.T. MA8 providing source duty. I find a lot of BA-only iems a poor pairing with my HA-501 due to their high sensitivity causing an intrusive background hiss. That is not an issue with the S6 unless you crank the damping factor all the way up. For mobile use my Shanling M0 was recruited for source duty and proved a fantastic pairing. Note that while I listen most of the time at quite low volumes, the S6 Rui really comes alive at moderate to high volumes. Those of you who tend to listen loud will get more out of this earphone than those than listen quietly.

Personal Preferences:

I listen primarily to various EDM sub-genres (liquid drum and bass, breakbeat, drumstep, etc.), hip hop, and classic rock. My preferences for earphone tuning are quite relaxed and as such their is no one signature I look for. The HiFiMAN RE800 Silver, Brainwavz B400, and Massdrop x MeeAudio Planamic are examples of earphones with wildly varied signatures that are enjoyable for different reasons. I generally listen at very low volumes, so keep this in mind when perusing my thoughts on how an earphone sounds.

  • Driver: 6 balanced armatures (Sonion bass x2, Knowles mids x2, Knowles treble x2)
  • Frequency Response: 15Hz - 20Hz
  • Sensitivity: 113dB/mW
  • Impedance: 20ohms
  • Isolation: 26dB
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Packaging and Accessories:

The S6 Rui arrives in a very downplayed cardboard box with little in the way of flourishes. The lid contains a simple outline of face plate with the Fearless logo in the top left corner while the side contain nothing. Flipping to the pack you find some specifications and a QR code. Lifting off the lid you're greeted to a long plastic protected by a flexible cardboard insert. Inside the case are the earphones and accessories. In all you get:
  • S6 Rui earphones
  • 8-core 0.78mm 2-pin braided cable
  • Hard plastic carrying case
  • Shirt clip
  • Velcro cable tie
  • Whirlwind tips (s/m/l)
  • Single flange silicone tips (s/m/l)
  • Foam tips (white, blue, and red)
  • Cleaning brush
  • Aluminum information plaque
While the unboxing experience is very basic, the accessory kit is not. I was truly surprised to see a set of medium Whirlwind tips preinstalled since I had only ever seen them included with KZ products in the past. Even more shocking was that paired with the S6 Rui, they actually sealed! This is the first earphone I can use them on. The shirt clip is nicely built but on the chunky side. Also, it can only be clipped above the y-split due to the thickness of the wire. It works well though. The information plaque is a really nice touch since it gives you the exact model designation (S6-2133) who made it and when (Yoyo on Feb 28, 2019), and where. That extra bit of personalization helps make a purchase feel special. Let's not forget that excellent case. The plastics are tough and textured making it scratch resistant. The interior is lined with foam to protect the contents. Unlike most cases, the hinge is is one one of the short ends with a thick clasp at the other keeping it securely shut. Waterproofing is about the only thing missing.

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Build, Comfort, and Isolation:

The S6 Rui doesn't do anything particularly new and special with their materials and body style, and that's a good thing. The acrylics feel amazing with that telltale softness to the touch that is typical of quality plastics. Since it is clear, you can see the layout of the drivers, the painfully accurate soldering job, the compact 3-way crossovers, as well as the sound guides and Knowles-style filters within them. There are no bubbles, or imperfections to be found anywhere. This particular example of the S6 Rui has a silver tinsel/wire face plate and visually it is quite stunning, especially when looking at it up close. The way the Fearless brand name and logo float above it is sweet too, and it does float as evident by the short shadows cast when tilting it in the light. It all looks extremely clean, tidy, and frankly quite impressive. Fearless has done an amazing job with the construction and visual style of the S6 Rui. My only concern is the lack of a nozzle lip which makes pairing tips very important. The shape of the nozzle makes the wrong tip subject to slipping off, more so than other earphones I've used. The stock tips are fine but when you start moving into third party alternatives be careful.

The cable impresses too with it's eight core, braided design and attention grabbing silver colouring. The sheath feels fairly tough but still retains good flexibility, though sharp bends do reveal some memory in the form of kinks that remain. They can easily be straightened out though. Another nice plus is that the sheath is not at all sticky so the cable doesn't catch on your clothes or skin, sliding smoothly over it instead. All of the hardware shares a consistent polished steel design which is refreshing. Other cables seems to pull from a generic parts pins and lack a cohesive look. The 90 degree angled jack is fairly beefy but has a 3mm extension to accommodate cases, and a stubby, strain relief that won't really do anything, not that a cable like this really needs it anyway. The tubular y-split tapers in at the edges drawing focus to the laser etched Fearless “W” logo imprinted on it. There is no strain relief entering or exiting here. Fearless thankfully eschewed memory wire for preformed ear guides which look to be made from heat shrink. The curvature is natural and it is just stiff enough to keep the cable in place during activity without causing issues with friction around the top of the ear. The 2-pin plugs are the only area I can draw criticism. The plugs are longer than the recession in the ear pieces so they stick out a bit leaving them susceptible to damage from bending. The blue ringed metal sheath surrounding the left plug is also screwed further down the plug leaving the cable looking a touch lopsided when installed. 99% of people wouldn't notice this, nor would they care if they saw it, but for someone like myself that like things to be uniformly mirrored, it is a little irritating. Now that I've noticed it, I can't unsee it. Also, while the pins fits in tightly, the right ear piece is prone to detaching unexpectedly. I have no idea why because it feels very secure, but it's happened a handful of times over my month or so of testing so it must be mentioned. Thankfully the ear piece has only ever fallen onto carpet so there has been no damage, as evidenced by my images which are almost always taken shortly before the review is written and posted. Nice to show any wear and tear a unit could pick up during testing since I try to use stuff as a daily whenever possible.

Thanks to a very ergonomic design, likely crafted from overlaying hundreds of ear impressions like many other brands have been doing as of late, the S6 Rui is a very comfortable earphone. However, as is usually the case with this style of shell this earphone is on the large side. It does contain 6 drivers per side and the accompanying crossovers, hardware for the 2-pin cables, and some filters after all. Still, as long as your ears aren't too small the S6 Rui is probably going to fit you like a dream, locking naturally into the outer ear to provide a stable, ear hugging fit. Another plus is that despite being a sealed design, the feeling of pressure you often get with sealed designs is absent, for me at least.

With 26dB of isolation, the sealed S6 Rui should be completely suitable for use in noisy areas. Using it in the local coffee shop was wonderful since I didn't have to increase the volume to drown out the chaos around me. The same could be said on a recent trip I took to a nearby city as a passenger in a noisy truck. Tossing on a set of the included foam tips makes things even better. Those who like to take their premium gear with them into the outside world will find the S6 Rui a solid companion.

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You're sitting on a beach in the middle of the ocean. The sun bathes you in it's rays of glorious life giving vitamin D. A salty, calm ocean breeze washes over you. This really is utter bliss. And the Fearless S6 is right there with you, caressing your ear holes to the soothing sounds of Dragonforce. What does this have to do with anything? Nothing really.

The S6 Rui has a mild u-shaped signature to my ears. Treble sees a meagre bit of elevation with a refreshingly even balance of presence and brilliance regions. Lower treble finds itself in a classy place, like Jim Douglas in “Herbie Goes to Monte Carlo”, with there being enough emphasis to provide a detailed sound that falls just short of being analytic all while avoiding the pitfalls and potential for harshness that go along with exaggerated boosting. Upper treble is much the same. It provides a grounded but airy note presentation with a silvery sparkly and shimmer to relevant notes. There is no harshness or anything overly aggressive going on with the S6 Rui's treble. It's easy on the ears but still very technically competent and with the snappy decay you expect from a balanced armature.

The midrange is full and engaging with strong vocals that peer through the mix despite not being jacked up and shoved forward as other earphones try to do. The clarity is stellar with a fair amount of micro-detail cutting through and pricking at your senses. This is the type of earphone that invites repeat listens of familiar tracks thanks to it's ability to represent everything available, so you might catch something you've missed in the past. It's a very honest and unbiased presentation with wonderful timbre that doesn't favour any particular frequencies, unlike something such as the RHA CL2 with it's stratospheric upper mid boost that nearly throws the entire presentation and timbre completely out of whack. But some people like that. If you do, the S6 Rui probably isn't for you.

The S6 Rui's low end is fantastic. Extension is very good for a balanced armature allowing it the ability to move some air and provide a decent bit of rumble. Sure, it rolls off earlier than many dynamics. BUT, at the same time it also extends further and provides a more impactful, engaging experience than many other dynamics. As with other aspects of the signature, the bass find that solid middle ground and makes it home. It sits in a favourable position being a little more emphasized than is considered “ideal” from a measurement perspective, but not so boosted so as to be called bassy or bass prominent. This style of presentation is very versatile since the S6 Rui can skip from genre to genre without the bass being overbearing or underrepresented. Add to that good dynamics and texture along with a realistic, not overly quick decay, and you have yourself some high quality bass.

The S6 Rui has a solid sound stage too, displaying a fair amount of width and additional depth. It can toss sounds away from the head and immerses you in music, just not quite as well as some other earphones I've heard. The depth to it's staging is where the magic happens giving music a very dynamic, multi-layered feel. This is supported by some impressive separation that ensures your music is congestion free. Imaging is also fantastic with crisp and accurate channel to channel transitions. Radiohead's “House of Cards” is a particularly enjoyable track with the S6 Rui and does a great job of showing off all of the above-mentioned aspects.

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Select Comparisons:

Fidue A85 Virgo (399.00 USD): The Virgo's triple driver hybrid setup has a much more mid-focused sound with roll off at either end. This makes it great for vocals and certain genres, but compared to the S6 Rui feels constricted. The S6's treble provides more shimmer, sparkle, and air thanks to a more prominent upper region. The Virgo's emphasis in the lower treble helps it with raw clarity and gives it an edge in mid-range note definition. The S6 Rui's mid-range is warmer and less forward with less detail but more accurate timbre. Bass on the A85 is slower with more mid- and upper-bass focus. Sub-bass quantity and extension is lacking, even compared to the S6's use of an armature where the Virgo is using a dynamic. The S6 is more textured too. Sound stage is surprisingly close with the Virgo feeling a touch larger and more open, but lacking the depth of the Fearless. Imaging, layering, and separation are all more prominent and accurate on the S6 Rui.

Build is split imo. While the Virgo's metal shells are immaculately crafted and drop dead gorgeous to look at, so is the S6 Rui. The two companies simply went about creating amazing looking and feeling products in completely different ways. The S6's cable is nicer though, looking more suitable for the price range while also handling better. Fit for me is also better with the Rui, though the Virgo's smaller, lower profile shells will certainly be more universal across a wider variety of users. Isolation easily goes to the sealer S6 Rui. The Virgo is heavily ventilated and has a very shallow insertion.

Overall I prefer the S6 Rui. The Virgo is a good sounding earphone but the limited end to end extension/emphasis leaves it feeling lacking compared to the S6 Rui. On the other hand, some will undoubtedly prefer it's more laid back, mid-heavy presentation.

Astrotec Delphinus5 (500.00 USD): The Delphinus5 is one of my favorite iems so the S6 Rui is coming in on the backfoot. That said, I am surprised at how well it holds up to Astrotec's flagship which as I understand has few fans. Both are armature only with the D5 featuring one less driver per side; 5 vs. 6. The D5 runs with all Knowles while the S6 Rui combines Sonion low-range with Knowles mid and high range drivers. I'm not a huge fan of Knowles low range drivers since I've been finding them outpaced by the low range drivers found in the KZ armature-only models. As such, I was not surprised to find myself enjoying the S6's low end more. It hits harder, digs deeper, and in general feels more engaging. The D5's low end gets the nod for texture and control, however. The D5's mid-range is more forward and articulate than on the S6 Rui, but is also colder and a bit less natural sounding thanks to a timbre that comes across more dry. Treble on the S6 Rui extends further and puts more emphasis on the upper regions while the D5 extends just enough to ensure you're not missing anything, and tosses emphasis at the lower treble. As such, the S6 Rui is brighter and more shimmery, but the D5 feels more forward and detailed. Imaging, layering, and separation is where the D5 always shines and it's no different here. The S6 does a better job than most of moving sound around in a realistic manner, but the D5 simply does it better. I feel like I'm surrounded by my music with the D5, something the S6 Rui falls just short of achieving. While I still like the D5 more, the S6 Rui provides a different experience and when in the right mood, can't be replaced by the D5.

In terms of build, this is basically a repeat of the Virgo comparison. A gorgeous acrylic design with flawless construction vs. a stunning aluminum gem, perfectly executed. While both are very comfortable, the D5's smaller size and rounded interior is superior. I like the D5's cable but the stiff, memory prone copper cable doesn't perform as well as the S6's plush offering. Isolation is quite close too with the S6 Rui pulling slightly ahead. Either would be suitable for a commuter wanting to bring with them a TOTL listening experience.

Overall I prefer the D5, but I wouldn't hesitate to recommend the S6 Rui over it. While the D5's flat tune is great from a technical standpoint, I can easily see someone finding it stuck up and boring next to the S6 Rui.

Final Thoughts:

While certainly not inexpensive to most of you out there (myself included), I still consider the S6 Rui a flat out bargain when compared to more expensive gear I have on hand. Not only does it hold it's own in terms of tuning and technical competence, but it is built just as well or better, has a stellar cable, is comfortable as all heck, isolates well, looks amazing, and comes with a great kit of extras.

The packaging could be flashier I suppose, but people seem not to care about stuff like because it's packaging and they're going to toss it out immediately anyway, or maybe it smells wonky so watch out! Hey, at least it's spacious and completely recyclable. Woo! The right ear piece detaching at random is more of a valid concern, though easily addressed by lightly bending the pins towards each other. You shouldn't have to do it, but unless you go Hulk on the pins it's a very easy and low risk fix. Other than that, criticisms of the S6 Rui are as tough to find as Waldo's most challenging adventures

If you're looking for a premium product and don't want to drop 500 USD to 1,000 USD on a unicorn, the S6 Rui is well worth an audition so you can see how good it is, then afterwards go home with one. This is one of the few products I've reviewed that is absolutely worth saving up for.

Thanks for reading!

- B9Scrambler

***** ***** ***** ***** *****​

Some Test Tunes:

Aesop Rock - Skelethon (Album)
Daft Punk - Random Access Memories (Album)
Elton John - Yellow Golden Brick Road (Album)
King Crimson - Lark's Tongues in Aspic (Album)
King Crimson - Starless and Bible Black (Track)
Supertramp - Crime of the Century (Album)
Infected Mushroom - Converting Vegetarians (Album)
Infected Mushroom - Legend of the Black Shawarma (Album)
Gorillaz - Plastic Beach (Album)
Massive Attack - Mezzanine (Album)
Fleetwood Mac - Rumors (Album)
Run the Jewels - Run the Jewels (Album)
The Prodigy - The Day is My Enemy (Album)
Tobacco - screw*d Up Friends (Album)
Felt - Felt 2 (A Tribute to Lisa Bone) (Album)


100+ Head-Fier
Pros: Very transparent in high mids region, coherent, high quality subbass, no siblance peaks, lively sounding iem.
Cons: Borderline level of high mids / highs so might be fatiguing to listen to. Not for people who likes smooth sound.
Probably I should say that I have experimented with many Chinese IEMs recently and have auditioned or owned majority of recent hype trains. I do not like fatiguing IEMs, I prefer to enjoy music instead of listening to details and figuring out if something extra is in there so I tend to enjoy an overall picture over small notes. That says that I like balanced, smooth IEM without any noticable peaks.

Purchase story

I have purchased my S6RUI from Linsoul and payed my own money because of snowball effect which was created by one of the famous Youtube IEM reviewers. They took about a week to be made and were shipped out very fast so I received them in about 2 weeks.

I would like to thank Linsoul Audio for great communication and Customer service.


S6RUi come in a generic box which has some similaritites with BGVP DMG and BGVP DM6 boxes. If you remember old Xiaomi boxes you would now what I am talking about.There are many different tips mostly with wide nozzle and several types of foam tips. I would rate this package as acceptable / good. Nothing I was surprised with but basically everything you would need.


Comfort & Isolation

These IEM are very comfortable. They have quite a comfortable shell which I personally see for the first time. Nothing hurts my ears and they fit them really great. I would rate their shell as 5 out of 5. I have shared these IEM with several different people and noone experienced any difficulties so it's great.

Considering the text above I have great Isolation with them. Not on the level of Etymotics but quite around maximum level of what you get from Universal IEM.



They focus more on subbass than on midbass and it's quality is around the top levels of what it might be in UIEM. I personally heard only one IEM which I consider to be on another level in terms of subbass quality and they were Sony IER-M9 but they are in a completely different price league so it's not a fair comparison. Additionally their bass can be tuned by using different types of eartips. The smaller the nozzle is the more subbass you get and with wider nozzle focus switches a bit to mid bass. I would say that both for the price and overall these have 9 out of 10 quality bass.


They tend to follow modern tendency of Harman like sound as it was mentioned many times. I personally do not really like the way it sounds in implementations I have heard so far (Sony MH755, Dirac HD MK II, S6RUI) so take it into consideration. I have heard that only N5005 have managed to do it right so far but that's just fancy words which are not backed by my own experience.

They lack some weight in lower mids so overall they sound very-very close to natural but still a bit on a thin side. Their high mids bump is done in a very professional way so they manage to be dynamic and focus that region without any weird peaks or cliffs. That makes them quite coherent and sound without any distortions, transparent like a crytal clear mirror.

However to my personal taste I find them being borderline fatiguing. Once you put them in your ears everything sounds great but after a while you find that you feel a bit tired because of their brightness. It is nowhere near something like Andromeda which are like "hearing killers" to me and an absolute fatiguing brightness machine but still If you prefer something smooth or more balanced you should take this into consideration.


There is quite a good feeling of air and separation between instruments. In direct comparison with Ibasso IT04 I found S6RUI to have more space and have an overall positioning slightly better even though not a mile ahead.
I would say that there are just enough highs to feel comfortable with them and does not feel that anything is lacking.

Overall sound verdict:

These would be great for people who wants a tad of brightness or sparkle in their sound. I would easily recommend them for people who enjoy subbass + detail retrieval as these IEM do it very good. Soundstrage and separation are also good but not the best I have heard. These sound very close to natural. I would not recommend these for people who are sensitive to brightness or who prefers smooth sound.


I would not compare these separately with other models but in more of a "free flow of thought" form way. Considering the current market state and fast evolving nature of Asian IEM market every day we get more and more choices. You have probably heard on this forum about some "High Quality 12 BA or FR12" models from China and in direct comparison with them 12BA model does not stand a single chance. I have no idea why this 12BA model has some crazy burn-in recommendation as it is quite broken in a way it is engineered in a first place. However sometimes Chinese OEM make something right and I speak about NK10 here. I have reviewed this model previously(about 6 month ago and my freind still owns a pair). They cost a bit less than S6RUi and in direct comparison I personally would say that they are less fatiguing. NK10 has safer highs mids/highs tuning, sounds more expansive with better separation and more air in sound. It definitely loses in subbass region and sometimes produces more distortions due to 10 BA being in it but eventually I find both models very close to each other. On the other hand something like IT04 costs more and does not stand out in quality over S6RUI. IT04 has more midbass, a bit thicker sound but less air and separation. Considering the price I don't think there is a point to go for IT04.

I would like to thank ElixBerd for making these graphs.

Orange are NK10 and purple are S6RUI, these are very close:

photo_2019-03-21_01-03-23 (2).jpg


This model does everything good and "subbass + detail retrieval area" great but it does not impress in "exceptional way". It's not cheap. In 400 USD price region you may get a lot of different IEMs. It is for people who prefers a bit of brightness and sparkle, for smooth sound lovers I would say "try before you buy". It is a very strong model but I personally would go for something like Sony IER- M7 as I prefer smoothness over detail(if we ignore the difference in price).