FIR AUDIO XENON 6 Review: Next-level gourmand Basshead luxury

-amazing bass performance
-kinetic DD rumble, grunt, resonance and vibrancy
-sub and mid bass layering
-physical bass sensition
-plenty of lower mids (warm and thick)
-smooth cohesive balanced W shape
-engaging dynamic rendering
-natural and densely rich timbre
-supremely enjoyable male and female vocal (wide and thick)
-excellent tone-timbre for sax, piano, cello, contrabass, violin
-warm but not dark mids
-wide and tall holographic spatiality
-snappy EST highs
-velvelty treble
-fun, engaging yet versatile and life like musicality

-not end word in term of technical performance
-not the best bass separation and definition (lack of texture)
-a hint foggy mid range (softed definition edge, surely due to open BA design)
-not very clean treble (again open BA design)
-EST tend to pick background noise
-EST tend to stole the show of other micro details or percussions
-EST go faster and add a sens of speed that not always match slower DD and BA presentation
-the IEM sensitivity isn’t stated (and seem high)
-my car doesn’t worth 4K$ so i can’t sell it to buy those


TONALITY: 9.2/10
SOUND VALUE: Cannot apply
(for me technical benefit is average but musical benefit is very high)

Just a little introduction to my audiophile journey and experience.
I’ve done audio review for about 7 years now, with an insatiable curiosity about sound value in all price range. But I didn’t limit myself to high sound benefit return since musicality have no price logic. In fact, I go from Westone ES2 custom IEM to budget chinese IEM, then try or review more than 300 earphones in all price range including Kinera Urd, Hifiman RE2000, Final A8000, UM Mext, Aroma Thunder, Sony Z1R, Shure KSE1500, 64audio Nio, Campfire Andromeda, Dita Fealty-Fidelity etc.
Yes, i’m crazy. But for an headfier, I think im temperate in fact.
I tend to favor musical balance over in-your-face technical performance, yet, when I go into critical listening I separate both for analyze. I’m very sensitive to timbre and tone naturalness and tend to dislike thin sounding IEM, but again, since I listen to very wide range of music from classical to jazz to Soul, R&B, Rock, Rap and stuffs, thin mids aren’t really an issue for lot of genre or anything without acoustic instrument or vocal.
I’m know to be not easily impress by IEM.
Sure, when we go into kilobucks one it tend to be less underwhelming than sub-100$ cheapies, but their very bad one like the Dita Fealty for ex, I don’t like Shure KSE1500 at all too since it’s a prime example of in-your-face all technical sound with thin timbre.
I love Nio, Z1R, A8000 and to some extend the Mext.

And did I love the Fir Audio Xenon 6 too? Well, we will see in this review!

Let’s begin by saying the Xe6 are a loan and I have zero obligation to review them. A Canadian fellow with way more money than me loan me this for 3 weeks. I remember how they arrive, I was doing a ”reviewer walk” with the Aroma Thunder, planning to find and keep critical listening momentum to finaly complete the review. I can easily get distract with other IEMs when an IEM I need to review don’t truely mesmerize me, which was the case with the Thunder. So, it was forced work we can say, i need to say focus but decide to do a stop at post office wishing their nothing to distract me. But the Fir Xenon 6 was there.
All the way back to home I was repeating myself: Eric, don’t be frail, stay focus on your critical listening impressions and don’t listen to Xenon 6 before at least writing the audio impression you pile up in your head. Be brave, be a man, be mature!
Then very first thing I do entering my home is throwing away the Thunder, runing into my bedroom like a kid back from halloween with it’s candies bag and put the Xe6 in my ears. I never pull them off until I was too sleepy at 2am. And report my Aroma Thunder review for days and days.
C’est la vie!

In fact, I didn’t even know the price of those nor that much about Fir Audio company, to be honnest, I even have prejudice about this company even if as an artist, I do enjoy their cartoon. Then i begin to read and understand the staff were working for 64audio. And I love 64audio. Then I read about kinetic bass and other tech they use, some taken from 64audio other exclusive to them and I was like: OK, it’s no amateur audio company, that’s legit audio engineer with a unique vision!

And then I see the price and barely fall from my chair. 4000$! OK! 2 times pricier than my Final A8000. But hey, it have more drivers and exotic tech.

Their no doubt that what fascinate me at very first listen was the bass experience like no other I ever heard. It was out of my head and in my head but pounding on my skin too, it was physical and musical and technicaly very competent in term of sub bass rumble and mid bass punch that doesn’t melt togheter yet have the natural warmth to it. But then the vocal come and go above this bass and whole spatiality was feeling so open, holographic and immersive that I know it was a love at first sight, i mean listen. This make me sad because I can’t afford those, I would sincerly love to tell you I hate the Xenon 6 but I don’t lie. But let say this review is not about sound value, just forget about this paradigm, it can’t be apply at IEM above 2000$, just can’t. Let’s say musical benefit return is high, but out of money context. Based on this premisse. We can begin the more serious review part.



The Xenon 6 is a tribrid earphone with 6 driver per side: 1 kinetic dynamic driver for lower bass, 4 open balanced armature for mid bass (1), mid range (2) and treble (1) and 1 electrostatic driver for ultra highs.
It use these 4 patented technology:
A hybrid conduction technology that takes the IEM sound experience to a whole new level. Kinetic Bass is a bass you can feel.

note: unique genius tech. this add sens of bass openess and depth as well as physical vibrance to bass punch and rumble. for proper effect, it need to be near your inner ears bone.

A pressure relief system that vents pressures that build up in a sealed ear canal. Greatly reducing listener fatigue so you can hear more and listen longer.

note: this indeed permit to have less loudness pressure, its used with near all IEM and just call venting, with Fir, it’s used for tuning module too that will inflict on sens of openess and resonance.
Open drivers with no sound tubes that radiate sound directly into the Sound Reactor which results in a much larger sound stage.

note: this is as well a rather common BA implementation, which have pros and cons, the pro is that it tend to avoid tubed BA shoutyness and agressivity and make it sound more wide in sound layers presentation, but it slow the attack speed and blur definition edge a bit, so we can say it’s relaxed BA presentation.

Proprietary technologies that provide industry leading durability and serviceability of our in-ear monitor products.

note: OK, i think Fir audio just love to patent everything….but housing is indeed very sturdy and durable.



The Xenon 6 are one of a kind when it come to construction and design. It’s made of thick machined stainless stell that seem extremely sturdy, and the back plate is made of sapphire glass that isn’t easy to scratch, which again promise rather good long term durability.
The shape is not the most organic, but don’t have hard angle to it that create discomfort, as well, it’s not very big, but the metal material used is quite heavy, so using a cable with ear hook is mandatory with those. Anyway, i never encounter discomfort even afte rlong listening session (8H non stop daily).
The nozzle is long and permit deep enough insertion, but ear tips holder isn’t very secure so some ear tips tend to slip, this is to be noted for those wanting to use short wide bore for example.
The 2pin connector aren’t embeded in the shell for secure connection, it’s nitpicky, but i think it would have been better.
It seem the connection can become looser with time, but this is inherent to 2pin connection made of plastic.


On the top of housing their a little screw, it’s for Atom XS modular tuning. You need a kind of small allen key to unscrew and change it, this isn’t very user friendly and one thing to note is that after some use, the screw module will loose their paint, making it near impossible to discern between each other. This is a concern to be noted (and solved).


The cable included is nice enough, nothing mind blowing for a 4000$ IEM, but not a ”joke cable” like some included with high end IEM like Aroma Thunder or Hifiman RE2000. It’s a strudy 8 cores cable, its not specify what type, but surely oxygen free silver plated. As well, it’s 4.4mm balanced plug.

Since those are loaner unit from a friend, I don’t have whole package, but it seem minimal anyway.



Let’s begin by saying this whole sound review is based on the Gold tuning module, which give an extra 2db bass boost and add slight hint of warmth. Whatever the tuning module, I don’t think the Xenon 6 will go bass light, I mean, it’s all about the kinetic bass + BA woofer here, and why make sugar less something that sound so sweet and yummy right?

So, as a whole, the Xenon 6 tonality can be summarize as a warm W shape that offer proper dynamic and presence for each main part of sound spectrum. It’s bassy, lushy and snappy. Its a balanced basshead set with thick yet well layered and holographic macro presentation. It’s not neutral nor boring sounding, it’s not analytical nor particularly impressive technicaly, the wow effect belong somewhere else with the Xenon 6, and yes, it begin with this mind buggling bass performance and flavor.

The bass of Xe6 was a big crush at first listen for me, and the full magic of matching a balanced armature woofer for mid bass with a big kinetic Dynamic driver for sub bass is certainly well achieve due to the cohesive, flexible and highly engaging result we are spoil with. This kind of bass isn’t possible with fully closed acoustic design since reverberance boost the rumble loudness pressure which is not an issue with the Xe6.
Exotic in dynamic rendering and natural in tone and timbre, the sub bass and mid bass are both thick and superbly layered, it’s not about boost in presence texture and definition but full physicality of both kick drum and bass line or kick natural decay you will get.
I want to talk about this ”physical oomph” kinetic bass give, where we can finally feel the inner vibration of this special euphonic boom.
Its layered over the sub bass, it’s a bone conductive impact that can’t be mimic in other way than from a speaker moving air outside of your head. This is the magic here that is so freakin addictive.
It tend to magnify overal sens of spatiality by adding a ”4th dimension” to it too.
So when the kick hit in loudness and presence, it have an extra body weight that will hit your temple, it can go gently to more energic depending of volume you listen to, thats another very important aspect of Kinetic Bass DD that perhaps haven’t been underline enough, I dont think people listening at super low volume will get same physical rumble and oomph experience.
How near of your temple is the Xe6 will inflict too on this, in 2 way, cleanliness and density of impact, it can go more open to more concentrate.
Now, this sub bass presentation is all but just about resonance trick too, since it’s dense and vibrant. For cello or contrabass it will add the bodied grunt we get in live concert when the player hit lower note with it’s bow, while for electric bass it will present each note in all fullness, with natural but a bit softed tone. We have a bit of warmth coloring that avoid over analytical texturing of instrument, but it doesn’t feel lacking. As well, I would not say the linear space between instruments is the widest, in fact, bass to lower mids transition is made in a thickly layered way, it’s not made with a ”silence dip” for crisp separation.
It’s luscious gourmand bass, with fast round warm kick and beefy holographic sub bass that dig deeper than you ever wish and induce a relaxed headbanging experience free of loudness fatigue or too radical basshead IEM.
The dynamic presentation not only permit to offer full sounding male and female vocal, or add density and naturalness to saxophone, bassoon and piano, but excell with genre like Jazz, electronic, Soul, R&B. The music genre that do a bit less well will be metal or very fast rock that need extreme speed and clean definition. But in fact, I would not consider the Xe6 a good choice for intense critical listener seeking true high fidelity presentation since here it’s all about a musical vision, and one that seem carved for my very ears.
The kinetic bass experience is physical, since you feel the rumble on your temple, but the magic here is that it feel beefy and well rounded too and as with whole Xe6 tonality, it magnify tone and timbre richness before presence grain, texture and definition. Believe me: their no other IEM that deliver this bass experience, and once you taste it, you can’t forget about it.


I rave so much about the bass, not only in this review but everywhere, but does it mean the mid range is subdued or underwhelming?
Not at all, quite the opposite in fact unless you seek for clean neutral presentation or highest transparency and resolution possible since here it’s all about body and tone lushness pleasure. Firstly, it seem lot of audio lover tend to forget about lower mid range, which is often non existent in lot of IEM, harman target being prime example of that. Presence of instrument being more about lower treble region, we have way too much anemic mids that hook our mind but left our hearth cold. Xenon 6 follow the opposite of this approach, while not lacking in minimal presence definition and texture, it tend to magnify the density and tactility of mid range instrument like piano, saxophone, violin or vocal. We have heavy note weight, we have wide and lush vocal presence with beautiful lower range coloring that magnify sens of air vibrancy within those instrument and soften a bit the hard edge of presence other earphones will choose to boost to the cost of sibilance or shoutyness.
Smooth, creamy and breathy are the vocal and it might be among the most beautiful I’ve ever heard. Again ,we have an holographic layering to main instrument which are widely stretched in center stage and so close to you it tend to embrace you like a cocoon.
This isn’t the type of mid range that will not make lipse noise invasive at all, nor the most energic in attack bite too, it tend to put the fundamental of instrument as the main tone focus, so everything sound melodious and effotless in musicality.
But it’s a bit warm too, so resolution is darken by that and again I feel the Xenon 6 do better for slow music or not too busy track, for classical symphony, you will struggle to perceive all instruments, especially in loud excited passage.
But for chamber orchestra, the result might blow your mind too, since all piano, cello and strings will offer fullness of presence, natural timbre and dynamic heavy weight. You will be in the middle of them, part of an holographic euphony like no other free of any displeasant harshness or treble grain.

Then there come the treble which have it’s EST driver as the star of the show we can say, because it’s the one responsible for extra air, fast snap and beautifull brillance. While low and mid treble is deal with open balanced armature that offer thick dense highs, the EST is perhaps only tonal sharpness of the Xe6. Sure, it feel a hint detached but not to the point of feeling wonky or out of place, it complete the holographic sound experience that the mix with open kinetic driver permit and wide open BAs mid range.
So the treble is rich in velvety sound layers and snappy micro details or percussions, have a sens of presence thickness and fast spot on treble spice. Yet, i would be hard pressed to call the highs clean or highly resoled, while calling it plain dark too, which isn’t the case. The attention of listening isn’t hooked by the energic attack of EST, which doesn’t always pick up whole range of percussions so this can affect proper pace of macro presentation, in the sens some percussions will sound more tamed in loudness and snap than other. Again, with more simple music, this isn’t an issue at all and in fact even with a problematic album like ”Art in Motion” from Aki Rissanen where the percussions timing is very important and drummer use wide range of percussions pitch with different sustain in resonance, it doesn’t annoy me unless I go into intense critical listening like right now. But this can be in fact pleasant too since at least we do have this percussions snap that are so addictive and engaging, and depending of complexity of drumming, it tend to fit perfectly any kick-snare-percussions rendering, add a vocal in the middle and bass line and you got the whole joyfull head shaing musicality you dream off.
Because everything have weight or airy tactility with the Xe6, even the treble, nothing sound too light or thin. The open balanced armature offer effortless and fatigue free violin and eletric guitar, high pitch of saxophone sound suddenly full in harmonic, not just about high pitch concentration. You don’t have any BA timbre, fuzzyness or metallic sheen (appart from EST with well, metallic instrument).
And I was happy to be able to appreciate the clavichord of Pierre Hantai with the Xe6, even if not perfectly restitute, the speedy playing was well timed and brilliant enough even if short on decay and natural resonance and not the sharpest in note definition. I can say the same for Harp, but when low and highs harmonic are play fastly some resonance bloom can unbalance the rendering. In fact, it just underline the peculiar mix of tamed low and mid treble edge and sharper, cleaner and crisper upper highs.
All in all, I could just have write this: smooth but sparkly treble.

The spatial presentation is quite incredible with the Xe6, if you are familiar with term ”holographic” it’s the first word that come to my mind, but a stretched multi-dimension one. The headroom is very wide and tall, and do have a sens of depth but not a clean or very airy one, yet, we do have extra stereo openess from EST driver that add deth, not just in center stage since nothing sound distant or far from you with the Xe6, yet it’s very spacious. It’s really like having 5.1 surround speakers around you, at about 1 meter distance and a sub woofer in the back of your head.

But this doesn’t mean you get the most accurate imaging, because for monitoring instrument you need to be position at some distance from the band, here your in the middle of it so you are literally into the mid range and have stereo separation for treble and bass. When it’s a track without bass rumble or resonance, it will be easier to pin point instrument placement but all in all the Xe6 are no master of static instrument placement.


While the Xe6 impedance of 28ohm is stated, ackwardly the sensitivity isn’t. I’m not sure to understand the legitimicy to omit this important information, but my guess is that sentivity is rather high, perhaps between 120 and 125db to give a vague (and safe) approximation. I conclude this because these are very easy to drive and even benefit from low gain from both Moondrop 4.4m and Hiby RS6, at high gain it will tend to pick up noise and be more agressive in dynamic, overly excited we can say, which affect negatively overall smoothness of the tonality.
So while I would not say they benefit from amping power, I do think pairing the Xe6 with clean and smooth audio source is important for making them scale up, low output impedance and low current gain is suggested. But this doesn’t mean they pair well with dead flat amp like the SMSL SH9, which seem to damp dynamic of bass rendering making the Xe6 sound near cold neutral, which is a infamy!
Pairing isn’t always previsible in result and my favorite one wasn’t with most expensive DAP like Questyle QP2R or Hiby RS6, nope, it was with the humble dongle Moondrop Dawn 4.4 which seem to add sens of openess, doesn’t have bass roll off and embrace the W shape dynamic beautifully.

Now, the ear tips too are important to achieve full sound experience of the Xe6, KBear 07 was my choice to get most open and full bodied tonality, as well as having the proper fit to have kinetic bass port near my temple, this is important to get proper bass sensation.

Cable to a less extend will inflict on dynamic rendering and how clean can go the Xe6, stock cable isn’t bad but seem to make the dynamic more in your face, adding hint of loudness gain, so I choose the Tri Grace S 6N litz copper silver plated cable for a slightly crisper result with improved layering articulation and overall more organic tonality with lively effortless dynamic.



VS UM MEXT (1DD+4BA+1BC-1100$)

The Mext tribrid don’t use Bone conduction transmission for purpose at all, it’s a wide range that cover 200hz to 7000hz region by adding presence details and magnifying sens of resolution and transparency. So, firstly, they sound more vivid and crisp, we can say more neutral even if quite bassy. We are sure more invade with micro details as well as a more analytical sens of spatiality. Everything sound cleaner, yet thinner too. Everything but bass, which is in fact warmest part of Mext tonality, and it feel sloppy and lacking well rounded definition which the Xe6 offer, as well it’s less punchy and we struggle to discern kick and bass line dynamic way more than Xe6, so more U shape bass in that regard. Then the mids is all about presence and have colder timbre, female vocal are more stick in your head, less wide and dense in presence and more agressive in loudness so here you will hear those lipsy details if you care about them unlike the warm thicker lusher mid range of Xe6.
The treble is the part Xe6 feel notably inferior and darker, as said, we have more details but attack speed, control and snap is better with the Mext too. Definition and texture of instrument is edgier and cleaner, highs are more open and airy, attack lead of violin is more abrasive and realist and unlike with Xe6, we will never confound by error cello and violin.
Spatiality wise, the Xe6 is slighlty wider, notably taller but less deep and clean than the Mext. Imaging isn’t really the highlight of these so it’s no surprise the Mext surpass them in that regard, layering is more transparent, instrument separation is cleaner and sharper and positioning more accurate.

All in all, I would say the UM Mext is superior technicaly in every department but bass while it offer a colder more analytical musicality that doesn’t trigger any emotional response in me, unlike the overwhelming one of the Xenon 6.

VS FINAL A8000 (1x pure beryllium DD-2000$):

Ok, this is a big deal since these are among my fav IEM ever…yet, the tonality have nothing to do with the Xenon 6 here, even less so than the Mext. So if the Xe6 are warm W shape, the A8K are vivid bright W shape with less boosted bass and mids and more focus and edgy treble. Here, it’s not the bass of A8K that wake you up but its crazy fast and talented treble only a great quality pure beryllium driver can offer. Listening to same music with the A8K make you feel it play in higher BPM and if the drivers of Xe6 were trying to run against it, only the EST will go to finish line.
So the bass is more textured and less boomy and euphonic thant Xe6, it’s less heavy in punch and less dense in timbre, the rumble is thinner too and not as sustain, separation with mids is cleaner, attack is faster and tighter and overal lower instrument resolution is better define.
Mids are brighter and thinner and more agressive and prompt to sibilance with A8K, it sound more open due to more recessed center stage and offer way crisper resolution. Definition of each instrument is edgier and clearer, and even if greatly textured, transparency of instruments are higher with A8K.
The the treble which is star of the show of A8K certainly put to shame the Xe6 since here we have more sparkle and natural decay than the Mext and perfect mix of highs fullness and crunchyness. These sure permit to deal better with fast busy track as well as offering proper bite to violin or electric guitar, so for metal head the A8000 is a better bet unless treble sensitive.
Spatiality is similar in wideness but inch taller with the Xe6, again, it lack the deepness of A8K. Imaging is intensely superior with A8K both in accuracy and proper space between instrument as well as greater amount of sound layers that can coexist at same time.

All in all, I will not sell the A8K to get the Xe6, and in fact would love to have both due to the fact they complement each other perfectly. But the mind blown here is the fact a single dynamic driver can offer superior technical performance than a 4000$ tribrid.


Ok, we are into big boi battle here and well, only thing these 2 have in common is the overall natural and laiback musicality, presented in a very different manner and tonal balance.
The Thunder is more neutral to mid centric with sub bass boost while Xe6 is more bassy L shape to warm W shape. What hit first is how more closed and intimate sound the Thunder compared to wider more open and holographic sounding Xe6.
Then it’s the bass, which is more boosted in punch, deeper in rumble and extension and more physical with the Xe6 (especially with bass tuning module), the rumble is more sustain thich and vibrant, it feel better layered too, the kinetic DD make us think their 2DD in there, bypassing limit of lower end acoustic law. With Thunder, kick and sub bass line can feel on same level and lack proper articulation difference in dynamism, while the Xe6 can offer both full bodied bass line and kick punch without canceling each other dynamism.
The mids are notably fuller sounding and more natural, vocal blossom in a wide way and feel more compressed and artificial with the Thunder. Timbre is denser and better in timbral balance fullness. Its not as detailed and transparent, yet, sound layer have more space for proper articulation.We can say Focus mode is slightly more similar in tonality, but suddenly darker, so again, its Harmonic mode i compare too here. Treble is the part we technical performance is superior with the Thunder, yet, less open and musical as well as less sparkly. EST offer sharper brilliance and more decay to sparkle. When it come to lower treble, it’s smoother too but fuller, so violin sound more natural and bodied, lusher than Thunder. Overall treble is thinner and colder with the Thunder too.
Spatiality is night and day difference here, the Xenon 6 is way way wider and taller, more holographic and center stage isn’t as recessed so it’s a bit less deep than Thunder that have a ”tunnel vision” spatiality.
Imaging is more realist with the Xe6 but your even more in middle of music, it’s more 3D and holographic, while it feel more static with extra highs positioning for the Thunder.

All in all, the Fir Xe6 sound more musical and less technical than the Thunder, offer more mids body and lush presence as well as more physical and punchy bass experience and smoother but sparklier treble. Their no doubt the musicality is way more engaging and emotional with Xe6 and could justify an impulsive car selling to enjoy this sound experience, while for the Thunder I will not even sale my rusted old bike.



The Fir Audio Xe6 offer a warm W shape signature, that extract all main aspects of music very well, not over boosting texture or details and instead favoring fullness and naturalness of tone and timbre, without going dark due to a quite snappy EST.

Not only the bass unique dynamic presentation is fantastic, but both male and Female vocal are incredible too, perhaps my favorite from all IEM i’ve tested yet, they are addictively dense-wide-lushly-textured enough with creamy but not dark upper mids.

The Fir Xenon 6 isn’t about trying to achieve an overly serious and austere high fidelity musicality that will put you distant from your favorite musician, instead it put the listener right in the middle of the band, well setted on a sub woofer.
Sure the price tag is high here, but when we know richer people can pay thousands of dollars for a fancy pizza with foie gras and truffle on it, I do think such a listening pleasure isn’t that crazily overpriced, it’s just out of common sound value concept were technical performance and ultra high resolution is main concern.
Yet, I do think Fir Audio could go all in basshead IEM one day and push the kinetic DD tech to it’s paroxysm, and it would be a wise idea to make it more affordable for the mass, which love bass too. And vocal.
Until then, time for me to go stole a bank and get my own Xe6 pair!

Highly recommended (if you can afford it)

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