Fir Audio occupies a pretty important space in the high-end IEM market. While I haven’t been particularly impressed by some of their more recent releases, there are a few Fir Audio sets that left a very positive impression on me when I had the opportunity to spend time with them.
The Xe6, RN6 and M5 are probably the ones that stayed with me the most, each offering something rather distinctive and very much in line with what I associate with Fir Audio.
After posting my impressions of the Xe6 on Head-Fi, it became pretty clear that Fir still has plenty of fans who appreciate what the company does, and after spending more time with the Xe6, I can certainly understand why.
In my opinion, the Xe6 represents the pinnacle of the Fir Audio sound.

So, what is Xenon 6 and makes the Xe6 so special?
Fir Audio Xenon 6 — Technical Specifications
- Driver configuration: 6 drivers per side
- 1 × 10mm Kinetic Bass Dynamic Driver
- 2 × OpenDriver BA for mids
- 1 × OpenDriver BA for high-mids
- 1 × OpenDriver BA for highs with Sound Reflector
- 1 × OpenDriver electrostatic driver for ultra-highs
- Frequency range: 20Hz–20kHz
- Impedance: 28Ω
- Technology: Kinetic Bass, ATOM Venting, Open Acoustics
- Fit: Universal and Custom
- Universal shell: Machined stainless steel with sapphire glass faceplates
- Modules: ATOM XS interchangeable modules (UIEM)
- Connector: 2 Pin
- Price: US$3,899
What makes Xe6 special ?! For me, it starts with the bass.
The Xe6 has one of those bass presentations that is difficult to properly describe with measurements or frequency-response graphs alone, attached a recent graph nonetheless

It is huge, deep, physical and heavily textured. This is not simply bass that you hear, but depending on the track and the seal, it is bass that you can actually feel. There is a particular physicality to the Xe6 that makes the entire presentation feel bigger and more immersive. The bass has plenty of weight and presence, it carries an impressive amount of texture As well, which prevents it from becoming just a sheer of low-frequency block.
Is a spacious, almost spherical presentation that can be incredibly soothing and immersive, which is probably where the Xe6 separates itself from many other bass-heavy sets I have heard.
One of the more interesting aspects for me is the BCD-like effect, particularly around the mid-bass and lower vocal region. It gives certain instruments and vocals an additional sense of physicality and texture, almost as if there is more information being transmitted through the shell rather than simply reproduced acoustically.
It is relatively easy to pick up on this effect with the Xe6. The stage feels grander, imaging and layering benefit from it, and the bass, especially the mid-bass, becomes more organic and integrated into the overall presentation and contributes to the character of the Xe6 rather than becoming a gimmick.
The mid-bass can occasionally become dominant enough to overlap with the lower vocal region. Depending on the recording, this can introduce a slight graininess or make the lower mids feel a little less clean than they otherwise could be.


For someone who prefers a leaner, cleaner presentation, or simply wants a bass which is bold, but it maintains a more pristine lower region, the Xe6 will probably be quite the opposite of what they are looking for.
Fir’s gold IEM is unapologetically a bass-heavy and there is no cable or source to take that mid-bass presence away.
The good news is that the bass is so well integrated into the overall character that I rarely feel it is simply there for the sake of quantity. But there are moments where I would have preferred slightly more separation between the mid-bass and lower vocals.
Chain – cable pairing, ATOM modules , source and eartips
Source, cable, tips and, perhaps most importantly, fit and seal can make a surprisingly noticeable difference with the Xenon 6. Getting the right fit is essential if you want to experience the full depth, physicality and overall presentation this set is capable of.
When it comes to cable pairing, I would also be somewhat mindful of what you choose.
Starting with the stock cable, which is easily one of the most comfortable cables I have used, it does a very good job of letting the Xenon 6 perform as intended. There is really very little to fault here, and I could easily see someone sticking with the stock cable and being perfectly happy with the result.
That said, a more serious upgrade cable can still take the Xenon 6 a few notches further, particularly when it comes to refinement, control and overall presentation.

The Xe6 already has plenty of warmth and low-end authority, so pairing it with an excessively bass-forward or warm cable can push the presentation further in a wrong direction. Ulan 8w , and. Although i love this cable, did exactly this. With a more balanced chain, I find the Xe6 easier to appreciate for what it does rather than simply for how much bass it produces. Eletech The Fifth Ode and the Plussound Copper Fusion Hybrid 6w are both very nice and i would highly recommend each with Xe6
The ATOM modules also provide some additional flexibility, allowing the tuning to be adjusted to a certain degree. They are useful, although I have to admit that changing them is somewhat fiddly. It is certainly not something I would want to do constantly depending on the music I am listening to.
Packaging and accessories
For an IEM at this level, I found the packaging somewhat underwhelming. It doesn’t really give the same impression of occasion that the Xe6 itself manages to create once you start listening, but ultimately, the packaging is probably the least important part of the experience.
Final toughs
- Huge, physical and textured bass.
- An expansive and immersive stage.
- A surprisingly effective and pleasant BCD-like sense of physicality.
- A rich and soothing presentation.
- A tuning that is unmistakably Fir.
There are compromises, of course, but Xenon offers something pretty unique which i think no other IEM can. It is certainly not a “one size fits all” IEM, but if it does, it is truly unique and you will feel like you discovered something special which is difficult to replicate.
For me, after having spent time with quite a few Fir Audio sets, the Xe6 remains the one that best represents what I personally associate with the Fir sound.






























