FiR Audio Radon 6 (Rn6)

The King Has Retuned

Pros: Excellent bass quantity/quality
Excellent mids
Excellent highs
Beautiful build quality
Great cable
swappable modules

Cons: Limited to 300 copies
Packaging/accessories could use some work
Understandably pricey

Rn6 Cable Front Back.JPG


Up for review today is the MUCH-revered FiR Radon 6 (Rn6) which I purchased at full price because of the kudos it was getting (and promptly threw up a little). FiR took the Xenon 6 (Xe6), kept the same drivers, retuned it, and fixed all of the complaints the Xe6 had. Now with lighter weight, a more durable finish, and an excellent cable, the Rn6 is ready to take on the current stable of TOTL IEMs for only $3,300 (yes, that’s still an exorbitant amount of money, but cheaper than almost every other TOTL IEM from the major market players). The Xe6 makes excellent use of its 1x Kinetic Bass 10mm Dynamic Driver, 2x OpenDriver Mid BA Driver, 1x OpenDriver High-Mid BA Driver, 1x OpenDriver High BA Driver (with Sound Reflector), and 1x OpenDriver Ultra-high Electrostatic Driver. It also has the ability to switch out ATOM XS modules to change the tuning and provide decibel reduction. Only 300 of these are being made…ever since it’s a 5-year anniversary model. It also still has the Xe6’s kinetic open bass port, albeit smaller in size – and it remains a tubeless design. Sweet. So how does it sound? Read on for the review.

Rn6 Case.JPG

Accessories/Earpads/Eartips (7/10):

Eesh, this is a tricky one. First off, it will take you probably 10 minutes to open the Rn6. Why? Because it has a sleeve on it that requires EXTREMELY careful removal and consistent shimmying to get it off the box. Five minutes later, once you get the sleeve off, there’s still a super tight box lid you have to remove from the box bottom – another five-minute process since it’s so tight. At last, you’re greeted by a FiR Space Force iron-on patch and the IEM itself with the cable attached. As I’ve learned on previous FiR IEMs, you will need to remove the foam that the IEMs are stuck into in order to remove them by pressing lightly from the bottom and slowly working them out from the top at the same time. If you don’t, you will bend the pins on your cable because the foam is TIGHT. Underneath the IEMs, you get a carrying case with a few random ear tips (like 5 sets) of various styles and types, none of which really make sense or lead to a good fit. As always, I’m using my Spinfit W1 tips since they’re the best I’ve found (You can buy them here if you want a set:

Fir Rn6 Modules.jpg

You also get a cleaning tool and 4 ATOM XS modules – maybe. You might only get 3 – it depends on if FiR is feeling generous and is including the Red module still (there was a rumor that they were going to start charging for the Red module, but I haven’t seen that happen yet). The ATOM XS modules change the tuning of the IEM and can add more bass and let in more outside noise. I’ve included a chart showing the differences above – yeah, there’s not a ton of difference, but I can speak from experience that the Gold module increases the bass by quite a noticeable amount. So as usual, it’s something you can play around with and find your preference – some love the Red’s neutrality, some love the Gold’s bass, or something in between – find what works for you. Overall, this is about the bare minimum that packaging should come with. It could use more ear tips – I’ll be using my Spinfit W1s as usual. There’s also not a lot to make you feel special about spending $3.3k. Oh, and it comes with an empty box inside…not kidding. It’s just a spacer box – fill it with stickers and extra ear tips or something FiR! A plastic FiR bunny even, but clearly your box is too big for what you’re including. Also, get rid of the sleeve and print the model directly on the box – make it feel like a $3.3k product. Anyway, 7/10 here for not at least including several sizes of one type of ear tip – Unique Melody does a better job here – heck, TRUTHEAR’s $20 HOLA has more ear tips included. Weak.

Rn6 Cable connectors.JPG

Cable (9/10):

Man, I love this cable. I just want to buy this cable from FiR and use it on all of my IEMs. It removes all of the complaints I had about the Scorpion cable. It does seem related to the Code23 cable but supposedly has no relation at all. That said, it’s flexible, comfortable, not too heavy, only a little microphonic, and the pins feel sturdier than a normal cable. The duplex twist is immensely well done and gorgeous. The cable is also pure silver with a copper coating (the opposite of what you usually find on a silver-plated copper (SPC) cable. It’s a joy to use and feels almost as nice as the cable on the Ronin and Mezzo LE. The microphonics are my only real complaint here – tapping on the cable while music is playing sends loud reverb through the cable and moving your head side-to-side causes the same effect. Still, it scratches every other itch and still beats the Multiverse Mentor’s annoying paracord finish and the Trifecta’s ribbon cable, so 9/10 points here.

Rn6 Back.JPG

Build Quality/Comfort (10/10):

Excellent. The build quality here feels like a lesson learned from the Xe6. Since the Rn6 is very clearly related to the Xe6 in size, driver count, etc., it seems that FiR took the negative of the Xe6 (namely the fragile finish) and improved it with a rugged black aluminum build while retaining the sapphire glass faceplate with gold flakes. These appear significantly more durable and don’t pick up fingerprints like it’s going out of style. They definitely have a better build quality and feel than their direct competitor, the Campfire Audio Trifecta (also ~$3,300).

Additionally, since they’re made from aluminum, they are a little bit lighter than the Xe6 (we’re talking a very small amount with something this tiny – and the new cable adds some weight). Still, they sit in my ears more easily than the Xe6, which was a big complaint for the Xe6. The Rn6 is EXTREMELY small when looking at all of the other TOTL IEMs on the market these days. They actually fit inside the inner parts of your ear, unlike IEMs like the Ronin and Mentor which take up orbit around your head and create their own gravity field. They have a significantly better fit and feel than the Jewel as well, though they are competing directly with the Trifecta on size, as those are also very small and light – the Rn6 are a little thicker than the Trifecta and will stick out of your ears more. So, it’s 10/10 points here for build quality and comfort.

Rn6 Box.JPG


I’ve included quite a few TOTL IEMs on the below since I was lucky enough to hear all of these in a short period of time and some might be wondering which of these to choose from. Obviously, the Xe6 has the most bass, followed closely by the Rn6 and Trifecta, and lastly by the Jewel. Keep in mind that the Frequency Response Graph (FRG) can’t capture the kinetic bass the Rn6 and Xe6 have since that speaker is on the outside of the microphone – so those two are likely a little higher in the low-end. The mids among all 4 are all over the place with the Jewel showing the most pronounced mids and the Trifecta having the biggest dip. Lastly, the highs are all over the place with the FiR-io brothers being relatively flat and neutral while the Trifecta is skiing a black diamond and the Jewel drops the treble like it’s hot. The songs below are designed to figure out what all of that means, so feel free to read all 4 reviews to see what the FRG can’t tell you.

Rn6 Trifecta Jewel.png

I am powering these, as usual, off of my HiBy RS8 with the A/B amp on medium gain at ~40/100 volume, so they’re nowhere near as efficient as the Trifectas are. I’m using the stock cable with a 4.4mm jack and Spinfit W1 ear tips (my favorite) through Tidal Hi-Fi with MQA and lossless files as well.

Lows (20/20):

I’m starting off with the Mid-bass/Sub-bass test I’m using David Guetta’s “I’m Good (Blue).” Holy crap, that’s some good bass. I can really feel the impact here (kinetic bass) without it having the extra unwanted reverb the Xe6 has. The sub-bass is intense here, and really good. This is truly the evolution of the Xe6’s bass – all of the quantity without the unwanted quality. The mids still manage to come through here quite clearly as well. It’s uncommon for me to have a DD on this song that avoids that Honda Civic with 10” subs rattle on this song – the Rn6 does that. 10/10 points.

Up next is Demon Hunter’s “I Am A Stone,” which I use to test whether the bass is too strong and overwhelms the mids as that is just as important as how strong/good the bass is. Typically, if the bass is excellent on the previous song, it’s overwhelming on this song – with only a few exceptions that have gotten good scores on both. The Rn6 is one of those IEMs. FiR managed to take the weakness of the Xe6 and turn it into a strength of the Rn6. By decreasing the size of the kinetic bass hole on the IEM, they’ve managed to keep most of the Xe6’s bass, but without it bleeding into the mids like the Xe6. What you end up with is a wonderfully bassy IEM that still has a good focus on the mids where they can be clearly heard despite the bass rumble. I don’t have a single complaint here, and the soundstage is excellent – this is about as perfect as lows can get – 10/10 points.

Mids (19/20):

Weaving The Fate’s “The Fall” is my test song for clean/dirty guitars and vocals with background instruments to see how clearly the vocals can be heard. Here is where we really begin to see how good the resolution and clarity of the Rn6 is. Not only are the intro clean guitars excellent, but the dirty guitars come in with all of the details you could possibly want – without losing the drums or cymbals – which are equally presented. The vocals of course sound great and have a nice forward focus, even during the chorus, which can easily get muddy on a lot of IEMs. Again, I can’t find a complaint with this song – 6/6 points.

Staind’s “Something to Remind You” has clean electric guitars and wonderful vocals – this song tests vocal quality and background noise. Wow, the bass guitar comes in nicely without blocking out the vocals – probably one of the few times I’ve ever heard separation and detail this good – ever. The Rn6 continues to amaze me with how it can introduce a high bass quantity without it overwhelming the mids or highs. Simply ethereal how it pulls this off. There is still the fingers-on-strings level of detail (without it being annoying) as well as a great focus on Aaron Lewis’s voice and all of the intricacies that entails. 7/7 points – just wow.

To test classical instruments in the mids, I’m using The Piano Guys’ “Code Name Vivaldi.” Again, a ton of detail and an excellent balance are achieved here with this song. The cellos all come in cleanly, both the low and mid cellos. The piano can be heard quite clearly with full depth and body. The only thing missing here is a little of that emotional feeling that I want from this song that IEMs like the Trifecta can deliver. The Rn6 is like that 5-star restaurant dish that’s missing the soul your favorite local restaurant can put into their meals. I’m going with a 6/7 here because this song SHOULD be an emotional experience, not a technical experience.

Highs (18/20):

To test sibilance on headphones I use Panic! At The Disco’s “High Hopes.” Yep, there’s some sibilance here on the “S” sounds. That shouldn’t be surprising since almost every IEM has sibilance here if they want resolving highs at all. That said, it’s better than most (somehow) and earns the Rn6 a 4/6 on this song.

Dream Theater’s “The Alien,” is the highs test song I use to see if the cymbals/high-hats/snare drum can be clearly heard and distinguished from the rest of the music (also good for instrument separation.) The cymbals come through very clearly on these, again proving that FiR set out to deliver one of the most balanced IEMs I’ve heard – possibly ever. The snare drums and the high-hats come through cleanly and with even more detail than the Trifecta. It’s impressive how well they can be heard on an IEM with excellent mids and lows. I had to go back and forth a couple of times here between the Trifecta and the Rn6 to determine that the Rn6 somehow even beats the Trifecta’s highs in detail and clarity. 7/7 here – top-tier, and I’m absolutely gob-smacked.

Michelle McLaughlin’s “Across The Burren” is another of my favorite highs/sharpness test songs as it can easily sound painful on some headphones. FiR worked some voodoo magic on these IEMs. There’s no sharpness here somehow while having excellent highs and great mids and amazing lows. I don’t know how they pulled this off in a 6-driver IEM at a price lower than almost every other TOTL IEM. 7/7 points here.

Soundstage/Instrument Separation/Imaging (9/10):

I use MGMT’s “Time to Pretend” to test soundstage, instrument separation, and imaging. The imaging on these is great, the soundstage is great, and as already mentioned, the instrument separation is excellent as well. These IEMs continue to amaze me on their technical capabilities. Do they compete with the Multiverse Mentor here? Sure, it’s close enough that I can award the Rn6 a full 10 points without feeling any sort of discomfort. 10/10 points – the Rn6 deserves the praise it has received from countless people who have heard it.


OK, so here’s where it gets tricky. I’d say that the closest competitor here is the Trifecta, one of my favorite IEMs. The Xe6 is honestly a completely different IEM despite the DNA these two share – it’s got the wubwubwub and is a more emotional experience than the Rn6, but with terrible bass bleed into almost every other frequency band. The Jewel has less body and breadth, partly due to the decreased bass, but similar clarity and technical ability.

So really, it comes down to the Trifecta as the closest IEM to the Rn6. They both have good bass quantity, though the Rn6 wins for quality and avoids the bleed into the mids that the Trifecta got knocked for. Both have excellent mids, though the Trifecta has more “soul” than the Rn6 – that characteristic that you can’t quite put your finger on, but that makes it so you can FEEL the music better. That’s how I’d describe the Trifecta vs just about every IEM out there, and it’s the Trifecta’s main selling point. So while the Rn6 hits a LOT of the points you want from an IEM on the scorecard, the Trifecta will still make you feel the music better. That carries on to the highs as well – the Trifecta has some insane sibilance, which the Rn6 manages to tame a bit, and the Rn6’s highs are as good, or better than the Trifecta. The sibilance that both of these present also gives them some of the most resolving highs and damping that down can really ruin how they both present the music. So, for a more emotional experience, get the Trifecta. For better bass quality, less sibilance (but not none), and a more clinical experience – get the Rn6.

Rn6 Front.JPG


The Rn6 is a weird one for me. I was let down by its brother, the Xe6, on the scoring chart, but the Xe6 was also instantly super likable with casual listening. The Rn6 crushed the scoring chart, but didn’t have that immediately likable sound during casual listening that the Xe6 had. Going directly from the Trifecta to the Rn6 was a legitimate letdown. After giving the Rn6 some time to burn in, it’s a technically impressive IEM, but it is missing some of the soul that the Trifecta imparts. The Rn6 is still probably the most balanced IEM I have heard in a VERY long time with excellent bass, excellent mids, and great highs – that in itself is a massive accomplishment for FiR. I’m curious to see what they come out with next – maybe something that combined the excellent technicalities of the Rn6 and the emotional connection of the Xe6. That’s a really tough ask since those are really hard qualities to put your finger on. And yes, this is the first IEM to earn over a 90 on the v3 scoring chart – pretty sweet.

Headphone Scoring (v3):
Accessories / Earpads / Eartips (10 pts):7​
Cable (10 pts):9​
Build Quality/ Design / Comfort (10 pts):10​
Lows (20 pts):20​
Mids (20 pts):19​
Highs (20 pts):18​
Soundstage / Instrument Separation / Imaging (10 pts):9​

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