Fir Audio is a new name for me, and I am excited to explore its library of high-end IEMs. One of their priciest models is the Radon 6, which is a limited anniversary model from $3,299. Does it deserve to be in the upper echelon of the IEM market? 

What You Get

• Radon 6 IEMs
• 2-pin gold-plated 4.4mm cable
• Genuine Leather Protective Case
• 3 sets of ATOM XS interchangeable modules
• 5 sets of ear tips
• Warranty card 

Look & Feel

The size of the shell itself is quite small, but it's made from high-grade materials. Its outside is a sleek all-black aluminum casing, and the faceplates are made from sapphire crystal glass. This makes for a beautiful earpiece and one that should be durable too. It{s the kind of quality you expect at this price. When worn, the Radon 6 is comfortable enough, but the fit isn't the most elegant one in the world. The housing holds itself steady just above your concha, while the ear tip does most of the work supporting it. I never thought they didn't fit right, but it doesn't sit as naturally compared to other IEMs in this range. 

Design

There is a series of 6 different drivers that I have not seen used before. It's a hybrid design that uses a 10mm dynamic unit that is a Kinetic Bass driver, which uses special conduction technology to wield better low-end results. The other drivers are a series of OpenDriver balanced armatures. There are two midrange BA drivers, one high mid-BA, one high BA, and one ultra-high electrostatic driver. The open driver technology does not use tubes and instead drives the signal through the Sound Reactor, another component that aims to expand the soundstage. 

Soundstage

If you try out the Radon 6 thinking that the soundstage and imaging will blow you away, you might be left a bit disappointed. That isn't to say that the Radon 6 is underwhelming here, its quite the opposite. You'll get an extensive sound display here, and the imaging is excellent. It expands the stereo image into a breathable space, but the individual performances appear closer to you than you might expect.

Separation and layering are still well intact, but the Radon 6 limits the space between each position. Spaciousness doesn't take a significant hit though, as the Radon 6 is still able to wrap around you. It delivers scale to the sound elements, filling in each space without constricting the stereo field. Each part of the mix has an identity, and the Radon 6 lets everything move around with grace. There isn't any part of the soundstage that isn't organized the way it should be, just don't expect the headspace to grow in any significant way. 

Low End

This is a fantastically gripping and articulate bass. It crawls up from the sub-bass and punches hard, forming a highly transparent and powerful response. The Radon accomplishes this tone without feeling like the bass is the main focus of the sound profile. It just has a rich timbre that is dispersed clearly in its space, and it makes for a truly engrossing sound. Tracks like "Pearls" by Jessie Ware showcase a lively groove that resonates mostly in your jaw, and the impacts are tight but full of color. It allows for a ton of texture that builds up quickly at a high resolution. The sub-bass has a tasteful gain, vibrating and lifting the frequencies just enough to supply tracks with satisfying movement.

Mids

There is a ton of detail in the midrange, and the Radon 6 delivers a dynamic and full response. The Radon 6 keeps its midrange frequencies pristine, making sure each sound is articulate and at its fullest transparency. Not a ton of room in conveyed, but the instruments and vocals are given a ton of personality. Their definition has a pluckiness to it that makes each note feel precise. The track "Rain" by Ryuichi Sakamoto delivers these incredibly realistic strings and piano keys that express every bit of detail they can, never restricted by recessed frequencies or cloudy tones. Vocals are exceptionally life-like here as well, offering a front-facing position and underlining crispness.

Highs

The purity of the sound signature reflects in the treble, offering exquisite detail and flavor to your tracks. There's a splashiness to the timbre that isn't too bright and a sibilant texture that isn't too abrasive. Mostly you just get easy-to-consume high-frequency details that are incredibly vivid. Certain performances have a fantastic shine to them, as they ring out and explore some admirable height. Crash cymbals and tambourines sparkle, adding a curtain of texture that overlays the sound signature with a decorative aura.  

Summary

The Fir Audio Radon 6 has an almost immaculate sound. Every section of the sound signature is exceptionally clean and expressive. The soundstage might not be the most holographic or open, but it gives the sound elements enough identity to stick out. Its design is unique and quite striking. Its driver configuration is also a designer rarely seen, as the technology used here is pretty exciting. The Radon 6 is very pricy and in the upper tier of audiophile IEMs, but if you have the cash, then the Radon 6 is one of the best around. 

The Fir Audio Radon 6 is available here.