Fearless Audio S6Rui – Review

Fearless Audio S6Rui

Fearless Audio S6Rui

| 4x Knowles Balanced Armatures | 2x Sonion Balanced Armatures | 3-way Crossover | 2x Sound Tubes |

🎧 We are reviewing the Fearless Audio S6Rui, a custom in-ear monitor with premium specs and drivers.

The Fearless Audio S6Rui features a hexa-driver, all-balanced armature configuration with a combination of the most reputable balanced armature’s manufacturers (Knowles and Sonion)

In addition to this, the Fearless Audio S6Rui packs a 3-way crossover and 2 sound tubes to handle the complex audio spectrum separation filtered to each specific driver.

Fearless Audio is a relatively young company but with already premium-class products such as the:

The Fearless Audio S6Rui, as being a custom IEM, can be personalized through an extra fee for the service. Part of the customizations include: “custom fit” (personalized earpieces through ear impressions on .obj or .stl files), custom faceplates (wood, transparent, custom picture and many others), custom metal sticker/logo. The “custom fit” service allows the creation of earpieces that have the exact ears shape of the buyer.

Nonetheless, buyers can opt for the universal model if no additional fee is paid (like the unit that we are reviewing). The universal S6Rui will come with transparent main housings that allow all inner components to be seen at bare sight and a silver-colored back plate with a textured pattern.

The cable of the Fearless Audio S6 Rui is nicely built with quality materials, fairly low microphonics, zero tangling issues and all-metal details such as cable bifurcation, cable strainer, 3.5mm jack section and the bi-pin connector ends – the 3.5mm jack has a pleasing carbon fiber alike, silver pattern.

The Fearless Audio S6Rui is part of the S line of the brand’s in-ear monitors including the:

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Fearless Audio S6Rui Review

Tests & Scores



Fearless Audio S6Rui weight in Ounces and Fearless Audio S6 Rui weight in grams.

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Accessories & Packaging

The Fearless Audio S6Rui unboxing results in: 6 pair of silicone eartips, 3 pair of spinning eartips, 4 pair of foam tips, a brush, a cable clip, a hard case, the detachable bi-pin cable and a metal plate with the serial number of the product that also serves a the warranty card.

On the other hand, the packaging has a quite simple design – as a reference, it is very similar to the one of the BGVP DM6.



Bass & Sub Bass

The Fearless Audio S6Rui offers punchy mid-bass and sufficiently deep sub-bass.

It’s bass exhibits a semi-dry style (which does not mean a shallow response) and tends to roll-off on the lowest end but shows an efficiently wide extension as to cover all genres.

Due to this, their overall bass sounds clean and controlled with no bouncy mid-bass, yet with an energetic tuning that will never get anemic.

Expect a bass response with a tight, fast but never thin personality.

Applying an EQ, unexpectedly, a crazy amount of sub-bass is unleashed (with a custom EQ aiming for an intense boost)


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Fearless Audio S6Rui
Fearless Audio S6Rui


Mids & Vocals

The Fearless Audio S6 Rui lower mids exhibit a negligible amount of mid-bass bleed that does not, excessively, interfere over their midrange sound – besides a clear addition of warmth and roundness.

In addition to this, their overall mids are clear with present male vocals that do not get shy nor sound distant. Furthermore, higher mids are very crisp but might risk of showing up some harshness when peaks arise – but rarely appearing in less-spiky tracks.

Their upper midrange’s active personality provides a good playground for tracks with calm female vocals. At the same time, their overall mids tuning adds remarkable clarity and separation and is able to provide a coherent response.

A custom EQ can be used to reduce part of their harshy peaks and to fine-tune their lower mids – still, their harshness will show up with tracks prone to it.


Fearless Audio S6 Rui
Fearless Audio S6 Rui


Highs & Treble

The Fearless Audio S6Rui highs are very bright, open and resolve good detail.

Their highs & treble personality is somewhat aggressive and will please listeners enjoying signatures that grant no muffled nor dull sound or headphones with emphasized brightness.

As expected with an in-ear monitor with this upper end tuning, piercing peaks can show up but sibilance will less frequently arise and, usually, with a milder intensity.

An EQ can grant substantial additional detail that can be squeezed out with, also, the incorporation of extra brightness. If carefully custom-tuned their piercing peaks can be partially sedated.


Fearless Audio S6Rui
Fearless Audio S6Rui


Sound Leak

The sound leaking out of the S6Rui is higher than on many average earphone, this is also because of it’s very high volume output that can tempt to crank way up the volume.


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Fearless Audio S6 RUI
Fearless Audio S6 RUI


Sound Isolation

The sound isolation provided by the Fearless Audio S6Rui is noticeably efficient, with a performance and capability substantially above most normal earphones.


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Fearless Audio S6Rui
Fearless Audio S6Rui



The super light weight of the overall earpieces, added to their rounded edges and curvy forms, result in a remarkably comfortable experience.

In addition to this, the very good cable with low microphonics and no tangling issues improves it’s usability and fit.

Moreover, the S6Rui can be personalized and can be bought with custom earpieces from the buyer’s ears impressions.


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Fearless Audio S6 RUI
Fearless Audio S6 RUI


Response to Equalization

The response to EQ of the Fearless Audio showed noticeable results with general improvement in mids, vocals, highs and treble with nearly no negative consequences.


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Fearless Audio S6Rui
Fearless Audio S6Rui

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Scores Scores

Fearless Audio S6Rui Scores

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Fearless Audio S6 RUI
Fearless Audio S6 RUI

Frequency Response (raw)

Fearless Audio S6Rui Frequency Response Curve

Fearless Audio S6Rui frequency response curve
Fearless Audio S6Rui frequency response curve

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Fearless Audio S6RUI
Fearless Audio S6RUI

Fearless Audio S6Rui Technical Specifications


Type Hexa
Driver Unit 6xBA
Sensitivity 113dB/mW
Power Capacity unknown
Impedance 20 ohms
Frequency Response 15-20,000Hz
Balanced Armatures Knowles + Sonion
Connectors Bi-pin
Cord Y-type
Cord Length 1.25m
Plug Stereo mini plug
Weight Approx. 8g
Supplied Accessories 14x Earphone tips; cable clip; case; metal plate

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Fearless Audio S6Rui FAQ

How many drivers does the Fearless Audio S6Rui have?

The Fearless Audio S6Rui is a hexa driver headphone. Which means that the Fearless Audio S6Rui has 6 drivers per side.

What type of headphone is the Fearless Audio S6Rui?

The Fearless Audio S6Rui is an in-ear headphone.

The Fearless Audio S6Rui is an open, semi-open or closed back headphone?

The Fearless Audio S6Rui is a closed back headphone.

Does the Fearless Audio S6Rui have a microphone?

The Fearless Audio S6Rui have a microphone and a remote.

What is the price of the Fearless Audio S6Rui?

You can check the most up-to-date price of the Fearless Audio S6Rui by following THIS LINK.

Where can I buy the Fearless Audio S6Rui?

You can buy the Fearless Audio S6Rui HERE

What cable do the Fearless Audio S6Rui have?

The Fearless Audio S6Rui have a detachable, Y-type cable.

What cable connection does the Fearless Audio S6Rui have?

The Fearless Audio S6Rui cable connection has a Bi-Pin interface .

Are there replacement cables for the Fearless Audio S6Rui ?

The Fearless Audio S6Rui cables can be replaced with compatible bi-pin  replacement cables.

Are there upgrade cables for the Fearless Audio S6Rui ?

The Fearless Audio S6Rui uses bi-pin cables which are very popular standard cables.

Does the Fearless Audio S6Rui have Bluetooth / The Fearless Audio S6Rui is a wireless headphone?

The Fearless Audio S6Rui does not have Bluetooth but you can buy Bluetooth cables to make the Fearless Audio S6Rui Bluetooth-enabled headphones. Or you can buy adapters such as the FiiO BTR3 to make it wireless Bluetooth.

Is the Fearless Audio S6Rui compatible with Apple devices?

The Fearless Audio S6Rui is fully compatible with Apple devices.

Is the Fearless Audio S6Rui compatible with Android devices?

The Fearless Audio S6Rui is fully compatible with Android devices.


Fearless Audio S6Rui Photos

We highly discourage anyone from trying to apply our testings to your own earphones, the risk of damaging or permanently breaking your iems is absolutely probable to happen. With our standardized equalization and amplification tests we push the limits of the earphones to the extreme. If anyway you decide to do so, we cannot be held responsible of the damage done to your equipment. Do it at your own risk.

Fearless Audio S6Rui





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