FiR Audio Krypton 5 Review

FiR Audio Krypton 5 Review

This is my first experience with FiR Audio, and I was particularly interested to try the one of their models, given that the ex-CEO of 64 Audio (a company that I love) now collaborates with this quickly emerging IEM brand. And it turns out he has brought some familiar designs to the table. Since all my sticky-fingered friends at MajorHifi got their hands on the most popular models, I’m left with the Krypton 5 to dip my toes into FiR’s sonic style. What can you expect from this pricy model in terms of personality and performance? And is it worth all the hype?

What’s in the Box?

  • FiR Audio Krypton 5
  • Braided Black 1.2m IEM cable with 4.4mm jack
  • Hard Leather Case
  • 3 Pairs Silicone Ear Tips
  • 3 Pairs Foam Ear Tips
  • ATOM XS Interchangeable Modules
  • IEM Cleaning Tool
  • ATOM Module Tool
  • FiR Audio “Space Force” Patch
  • Warranty Card
  • User Guide

Unboxing the FiR Audio Krypton 5.

Look and Feel

There’s no denying that craftsmanship of the Krypton 5 stands out. The shells are made from silver anodized aluminum, giving them premium feel. The face plates highlight the sapphire glass underneath, along with an understated silvery pattern and logo. For sure, this minimalist, yet thoughtful design makes for an elegant IEM.

FiR Audio Krypton 5 takes a few notes from 64 Audio.

FiR Audio Krypton 5 are slightly smaller than 64 Audio's models.

Like 64 Audio’s models, the shells lean on the smaller side, which I appreciate, given all the bulbous IEMs flooding the market. It’s a no nonsense fit that never stands out or becomes an issue. Comfortable with a decent seal. And since I never even thought about my ears when wearing them, the Krypton 5 gets full grades in the comfort department.


There are a few unique design points to mention here. The Krypton 5 employs a hybrid configuration without tubes. It combines a dynamic and a balanced armature to drive the low frequencies. The midrange frequencies use BA drivers, while another BA driver reproduces the treble. What sets these BA drivers apart is their unique open design. Instead of having a contained tube emitting sound, the drivers send sound directly into a specially constructed chamber called the Sound Reactor, developed by FIR Audio. And this design may come as no surprise, since 64 Audio’s tia drivers take a similar approach by also directing the sound waves at an angle into one’s ear.

The Krypton 5 has a frequency range of 20Hz to 20kHz and an impedance of 22 Ohms (sensitivity unspecified). So, these IEM’s are easy to drive, although they do benefit from increased power for optimal performance. For the purposes of this review, I kept it simple, and paired the Krypton 5 with the iBasso DC06 DAC/amp dongle.

The balanced 4.4mm cable sports a robust looking 2-pin connector, which seems to have been designed to be exceptionally reliable (again, much like 64 Audio’s cables). 

FiR Audio Krypton 5 cable has the sturdiest 2 pin connector on the market.

Finally, we get to the ATOM XS modules. FIR includes a T2 screwdriver in the box, which allows you to somewhat easily swap these modules and adjust the isolation values and bass response according to your preferences. The default silver module, for example, provides an isolation value of 15dB, while the black module delivers 13dB of isolation and trims the bass presence at the same time.

Sound Impressions


The soundstage is perhaps one of the Krypton 5’s best assets. There’s a grandness to the the soundscape, even though the imaging doesn’t stray far from the ear. Perhaps because of the less than pristine separation (more about this below), the layering is not as clean as you would expect for an IEM at this price point. But that being said, the height, depth and width are generously laid out to an almost tangible degree. So, what it lacks in tidiness, it makes up for with its fantastic imaging. And at the end of the day, the Krypton 5’s incredibly accurate and detailed instrument placement certainly makes for an engulfing and multidimensional listening experience.


The bass is deep and fleshy. There’s a wet fatness to this low-end, rather than a speedy tightness. The upper bass seems just as prominent (if not more so) than the lower bass, making for a notably warm sound. The sub-bass frequencies really rumble, but the vibration is felt around the jaw, rather than in the throat or chest.

In terms of transparency, there’s more smoothness than detail, bringing a graceful fluidity to acoustic instruments that sometimes comes at the expense of detail. That being said, the tone is enjoyable and will likely be highly satiating for bass enthusiasts in particular.


The low mids are massive on these IEMs, which I love, while the high mids stay back. This is a refreshing change to the more popular tuning that’s been hitting the market. That being said, there’s little clean delineation between the bass and the lower midrange. So, there is a slightly veiled feel here. And the Krypton 5 presents robust profile in general. Snares and other percussion hit soft and fat, and there’s a rounded resolve to instruments that would ordinarily feel tight and crisp. Unfortunately, these characteristics often take away from the resolution of the overall sound. Or at least appear to. And this ultimately means that the Krypton 5 is less ideal for acoustic music like folk than it is for modern genres like pop and EDM.


As we move up the frequency spectrum, the sound signature starts to clean up. And it’s in the highs where the Krypton 5 shows the most skill. You’ll hear ample detail in acoustic instruments like strings and trumpets, which are allowed to reveal all their subtle nuances in timbre and tone. The Krypton 5 also strikes a skillful balance between treble extension and smoothness, as the high peaks never pierce the ears, but at the same time, you never feel like you’re missing out on detail. And up in this range, you’ll finally hear a little crispness and shine. Still, even in the highs, the delivery remains rich and weighty.


The Krypton 5 is the right IEM for the right audiophile, though it probably won’t be heralded as a home run crowd pleaser. Those who can’t resist a thick, pounding, rumbly bass, super lush mids and smooth highs will likely gravitate towards this sound signature. But if you’re a stickler for resolution and you prefer your sound characteristics to be clean, lean, tight and bright, keep looking (especially given the startling price tag). In the same way, if you listen to a lot of acoustic music, where minute details and precision are required to fully appreciate the music, then you may want to search for a more delicate sound. But if you’re mainly a fan of modern music like pop, hip-hop and EDM, you’ll probably enjoy the rich, all-encompassing and admittedly charismatic sound signature that the Krypton 5 delivers.

You can buy the FiR Audio Krypton 5 at Audio 46.


  • (x1) 10mm Kinetic Bass Dynamic Driver
  • (x2) OpenDriver Balanced Armature for mids
  • (x1) OpenDriver Balanced Armature for high-mids
  • (x1) OpenDriver Balanced Armature for highs (with Sound Reflector)
  • Frequency Range: 20-20kHz
  • Impedance: 22Ω
  • Connector Type: 2-Pin 0.78mm

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Gabby is a composer, songwriter and music producer who has worked in the music, film, and commercial industries for too long. You can hit Gabby up at