FIR Audio XE6: look beyond sound

Hi friends!

In these troubled days, when the reality around us has become so fragile and defenseless, we offer, at least for the time of reading this article, to be transported to the world of perfect sound, where you can find peace and joy.

Today we have an appointment with the American company FIR Audio, whose creativity (that's right!) always arouses my admiration. Following the highly popular "M" series and VxV IEM, the brand has introduced its new premium line of in-ear monitors FRONTIER SERIES, which includes three models: NE4 (Neon 4), KR5 (Krypton 5) and XE6 ( Xenon 6). We will take a closer look at the latter.

All the three novelties listed above use the latest proprietary developments, namely: KINETIC BASS, ATOM VENTING, OPEN ACOUSTICS, RIGID TECHNOLOGIES, and TUBELESS DESIGN. I will talk about these know-hows in more detail in the review itself. In general, in my opinion, FIR Audio is one of the most technologically advanced and promising companies in portable sound. These guys never cease to amaze me. They do not throw big words, but work hard, they definitely go to the goal and achieve amazing results, and they do it extraordinary.

Like all FIR brand IEM/CIEMs, Xenon 6 has a hybrid design: here, as you might guess from the name of the model, there are six drivers of three types on board. In addition, there is also a replaceable Atom-X module, as well as a unique design implemented according to the Tubeless Design principle - the patented FIR Audio technology, which implies the rejection of acoustic tubes and the open design of the drivers themselves. As a result, not only the acoustic design of the case, but also the very structure of the internal components of the in-ear monitors, has been worked out with precision.

I already wrote about the M4, M5 and VxV models earlier, now it's the turn of the novelty.

Well, it's time for us to get directly acquainted with the new technological miracle, the flagship in CIEM performance, the amazing Xenon 6!


Text: Alexey Kashirskey (aka Hans Barbarossa)


Type: in-ear

Construction: hybrid

6 drivers per IEM/CIEM:

1x 10mm Kinetic Bass Dynamic Driver

1x OpenDriver Balanced Armature Driver for bass

2x OpenDriver Balanced Armature Driver for mids

1x OpenDriver Balanced Armature Driver for highs (with Sound Reflector)

1x OpenDriver Electrostatic Driver for ultra highs

Technology: Tubeless design, Atom Venting, Kinetic BASS, Open Acoustics, Rigid Technologies etc.

4 interchangeable Atom-X modules included

Freq. Range: 20-20kHz

Impedance: 28ohms

Cable: detachable - 1.2m/1.6m, connectors (2pin), jack-3.5mm

Design and sound without limits: CIEM individuality or UIEM versatility

Before starting the review itself, it should be noted that FIR Audio in-ear monitors can be ordered both in universal (IEM) and custom (CIEM) versions - the choice is up to the buyer.

Well, for those who have not yet encountered CIEM, I can assure you that the procedure for ordering a CIEM version is not difficult at all. You need to go to the site, register, go to the "Designer" menu, select the desired model, its design (appearance, connectors, cable length) and pay for the purchase. Then you go to the hearing center, make your impressions / imprints there and send them to the manufacturer. After that, look forward to the arrival of your exclusive in-ear monitors.

In our case, the XE6 model is made in CIEM version. And now it's time to go directly to the acquaintance with this technological six-driver miracle!

Appearance, kit, technology and ergonomics

For anyone who has ever listened to any FIR Audio in-ear monitors, the company's logo immediately gives the command to goosebumps to start running through the body in anticipation. And now, having cast the first glance at the box in which Xenon 6 are, I saw these perky bunny ears and immediately wanted to quickly unpack everything and immediately start testing. But in our business, there is no hurry, so let's still consider the packaging.



In addition to the logo on the front of the box, we see a graphic image of the XE6, which, like a space satellite, soar among the stars. In the lower right corner, there are three round icons representing the technologies used in the model: KINETIC BASS, ATOM VENTING and OPEN ACOUSTICS. And this is only part of the know-how.

The side of the box have adopted the golden sticker "XE6", the brand logo and the inscription indicating that the headphones belong to the new line "to New Frontiers". Detailed specifications are listed on the back of the package.



We remove the printing wrapper and find a black box, where we again encounter the FIR Audio logo in the form of rabbit ears, applied with gold embossing, from which sparkling sun rays scatter in all directions. And then my goosebumps began to dance the cancan!

We open the box and find what we are looking for: CIEM encrusted in a foam base with a replaceable cable (2pin / 3.5 mm) already installed, a cool leather puck case designed for storing and carrying in-ear monitors (in the CIEM version it also has the name of the happy XE6 owner engraved ), instructions and a round colored FIR Audio Space Force sticker. Yes, with these headphones you fly into space! But this is already a spoiler, back to inspection.



Three pairs (silver, gold and red) of Atom-X plug-in modules fit neatly inside the case, and another pair - black - is already installed in the CIEM. Next, we take out a brush to care for the sound pipes.

In general, the set is five-star, it has everything and a little more.

The CIEM acrylic shell in Matte Black is impeccably executed. This is a first-class performance, where every curve, every turn and bulge perfectly follows the shape of my auricle and ear canal - surgical precision! The design with its impeccability resembles the perfection of Michelangelo's sculptures. The shell itself is small and weighs almost nothing. This is perhaps one of the lightest CIEMs I know of. And the tactile sensations and ergonomics are simply incomparable!




Sound isolation is average, no worse and no better than most in-ear headphones. However, Xenon are not intended for the bustle of a big city, music in this quality should be enjoyed, fenced off from everyday frailty. Well, if you still want to take the headphones with you to the street or to ground public transport, then listening there will be quite comfortable. But for the subway, I suppose this may not be enough.

The CIEM is intended to be worn exclusively behind the ear.

When choosing the look of my CIEMs, I settled on a black matte shell and a similar faceplate with bunny ears (well, you're not surprised, really) on the left front panel, the model name "XE6" on the right. It turned out, as for me, just amazing: cute and very stylish - I personally am very close to this approach to design.


At the bottom of the faceplate panel fit a replaceable Atom-X module. ATOM (Air Transfering Open Module) venting is a miniature metal cylinder valve that reduces the sound pressure exerted on the eardrum, thereby protecting hearing. It bleeds the airlock that forms between the sound pipe and the eardrum, and also acts as an acoustic filter, which serves to fine-tune the sound of in-ear monitors.

It is appropriate to recall here that the XE6 uses "Tubeless Design" technology. There are no acoustic tubes and separate chambers for drivers in the design.



The sound pipe was covered by a removable metal mesh that protects the IEM/CIEM from moisture and sulfur. Another know-how of the brand is applied here - Rigid Snap Screen. Now you do not need to break the shell to manipulate the protective mesh, just take the tweezers, loosen and remove the clamping ring, then remove and clean or replace the mesh. Although I would still contact the manufacturer in case of a replacement.

Next to the sound pipe is a round port of an open dynamic driver. This is a grill-protected opening that transmits low-frequency signals directly to your ear cartilage. The same KINETIC BASS that you don't hear, but feel!



A little higher, closer to the 2pin connector, you can find another miniature hole, which is connected with the fastening of this connector. RIGID Technologies is a proprietary technology that FIR Audio claims provides exceptional reliability, durability and serviceability for in-ear monitors.

"The most durable 2-Pin connection on the market, rated for 1,000 connections without issue. Fits any 2-Pin standard. Featuring a revolutionary quadrant socket design that prevents the socket from getting loose."



The 26x8 Awg Satin Black twisted cable is made from pure copper and has the catchy name "Scorpion-C Wire". It is extremely light, elastic, nice and high quality, 2-pin connectors, jack L-shaped TRS 3.5 mm similar to Oyaide, the splitter is made in the same style. The cable length is 1.2 meters. When ordering, you can choose other connectors and connectors, cable length, as well as order a balanced connection 2.5 / 4.4mm.


As I mentioned, the XE6 has a hybrid circuit and is built around six drivers: one DD 10mm, four Open BA Driver and one Open Electrostatic Driver.

The "kinetic bass" speaker is responsible for the vibrations in the lowest part of the low-frequency register, one BA is responsible for the bass, its two brothers work out the mids, another BA - high frequencies and ESTAT - ultra-high frequencies.


Xenon 6 technologies are stuffed to capacity. Well, you can sing roulades to design. Before us is a masterpiece, no less! Let's find out why all these technologies were crammed into such a beautiful body. Let's move on to sound analysis.

Sound Impressions

Before listening, the headphones were burn-in for 70-80 hours.

Sound equipment: MyST DAC 1866OCU V.2, Lotoo paw Gold, iBasso DX240,DX300, iBasso 220 MAX, QLS QA-361, iFI iDSD  Diablo & iFi xDSD Gryphon.

With all devices, the XE6s sounded great, and their “voice” varied slightly depending on the sound source and the Atom-X modules used.



The sound of Xenon 6 can be described as perfectly balanced, noble, served in neutral-warm tones, with a slightly accentuated area in the lower register, absolutely natural mid-range, and high-frequency ranges.

This is an unusually smooth, polished and harmonious manner of sound extraction, served in an unusually comfortable, correct, studio-analogue form, with a warm "tube" tint. The tonal balance of the headphones is set up extremely competently in an analog manner.

FIR XE6 perfectly convey the volume and depth of an imaginary space: giving out a massive and organic picture with amazing elaboration of timbres and reverbs, convexly outlining the details of the composition, paying more attention to macro dynamics than micro contrast.

This is an unusually lively, dynamic and "ecological" manner. It's amazing how naturalistic Xenon 6 manages to convey the atmosphere of the songs being played!

Even some top models of full-size headphones did not dream of such a sound.

And of course, here we hear only the perfect coherence of the drivers and the complete absence of phase distortion.


The sound character, as you already know, can be tuned a little to your taste with the help of replaceable Atom-X modules. When ordering the CIEM version of the in-ear monitors, an option with a built-in, non-replaceable module is also available. And models of the Frontier series in the UIEM version come with ATOM XS modules.

Let's deal with the classification of modules:

silver - perhaps the most neutral,

black - neutral with a slight addition of low frequencies and deeper bass,

gold - the most bass with a slight accent in the upper register,

red - makes the sound a little more expressive due to a slight accent on the upper middle.

I opted for a black and silver Atom-X, although I think all options are beautiful in their own way.


The XE6s show a wide dynamic range and amazingly capture the volume of an imaginary space, with a sweeping stereo panorama and precise localization of apparent sound sources in space, where every musical instrument and every note played is precisely in its place. These CIEMs build a wide soundstage with amazing depth of virtual space. This is a massive soundscape, rendered in a smooth, neutral, velvety manner with a stark black background and embossed display of audio images in space.

Xenon 6 is able to impress the listener with its temperament, clear articulation, high resolution and extraordinary tonal accuracy.


The low-frequency range is gently boosted, which brings massiveness and depth to the sound and lays a solid foundation for the Mids. The blow is thick, precise and dense, going deep down. The bass is elastic, textured, with good speed. Despite its neutral-warm manner, the bass succeeds everywhere and flawlessly intertwines in the middle register, darkening the background and filling the listening compositions with a clear rhythmic basis, contrast and timbre variety. A clear clap, impact vibrations - everything is transmitted and felt clearly, accurately and smoothly, without hum and encroachment on other registers.

Well, the dynamic driver with KINETIC BASS allows you not only to hear the power of low frequencies, but also to feel them, to feel these vibrations that get under your skin! And no hint of mumbling, only the accuracy of timbres combined with excellent balance.

Where a beautiful and imposing manner is needed, Xenon 6 can gently roll with a pleasant, thick and velvety, charming bass. Well, if there is mass and pressure in the track you are listening to, then hold on: from the very depths of sound, a low-frequency earthquake will fall on you, and even with the presence effect in the form of kinetic bass energy.

Mids are smooth, natural, timbre rich and textured, delivered in a neutral manner. Here, every musical image or sound is clothed in flesh. This is a well-balanced and unusually harmonious performance, where all the elements of the composition are presented naturally, smoothly, large and multifaceted, with amazing accuracy and informativeness. The presentation of the mid-frequency register is simultaneously solid, plastic and extremely detailed. Power and delicacy, emotions and monitoring, drive and academic manners are wonderfully combined here. Every timbre, every vibration of the voice or trembling of the string is transmitted authentically and deeply. The vocal parts do not excite the ear with sharp bursts and do not upset the failures, everything is unusually smooth, natural and unconstrained. This is a well-balanced and at the same time sensitive performance, where all the elements of the composition are presented with extraordinary accuracy, large and multifaceted. It is worth noting the amazing transfer of the volume of imaginary space.

High frequencies are reproduced unusually clean, clear, smooth and harmonious. Their quantity and quality of working off raises no objections. The register is transmitted clearly, without excessive harshness and distortion, without drawing excessive attention to itself, in a completely neutral manner. Highs harmoniously contribute to the overall work, without whims and self-will, they give themselves up for the sake of harmony and balance of the entire frequency range.

Working out the upper register, every sound, nuance, whether it's touching a hi-hat or a cymbal, ringing a bell, everything sounds so clean and accurate that it deserves, in my opinion, the epithet "reference"! Special thanks to FIR Audio for such a polished study of the high-frequency range!



With any musical genre XE6 cope without problems. They reproduce both classical music, instrumental, jazz, electronics, rock, and brutal genres with extraordinary interest.


FIR Audio XE6 - an unprecedented model of in-ear monitors! Thanks to such extraordinary developments, for many years my interest in testing portable Hi-Fi, and in this case, real Hi-End, has not faded away.

Before us is TOTAL CIEM, which audiophiles around the world will dream of and which the audio industry will measure up to. I will say more, in order to create such a masterpiece, not enough talented engineering, you also need a visionary gift. XE6 actually get to the very edge of the studied universe of sound and look beyond it!

Of course, such a technological sound "rocket" sent into musical space has a corresponding cost. You can order Xenon, both in CIEM and UIEM versions, on the official website for $3899. The price tag, of course, frightens with the number of numbers in it, but for the most notorious admirers of the highest category of sound, I recommend without the slightest hesitation to make every effort to purchase the FIR Audio Xenon 6.


Sound, comfort, design, build quality and materials



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