My friend Darius (aka Skullar) was crazy enough to lend me his FiR Audio KR5 for the week-end. I could see fear in his eyes as he handed them to me and warned me: don’t you dare scratch them!

And when I saw the earphones, I understood. The KR5s look like they could get scratched just by looking at them. And I thought to myself: maybe I am the crazy one!

But then I got home and put them in my ears. And boy do these deliver.  

Before we go into sound and technical stuff, note that the shells are much smaller than most online pictures imply. I was expecting chunky shells but they are actually small. Their design is very refined and tasteful. Not as flashy as I expected. That’s a good thing in my book.  

The build quality is top notch as you would expect from FiR. These might be the easiest iems to service out there. FiR audio have allowed for various swappable parts, including the 2pin connector. A very good move.

Now onto the sound. In a nutshell, the KR5s have incredible bass, clear mids and probably the biggest, most open stage I have heard in a high end iem. On the less positive side, treble can be peaky at times. More on that later.

Let’s look at the graph:

This kind of signature with elevated mid bass is getting more popular. The new AuR audio Neon (impressions coming soon) has a similar low end signature.

And while both iems deliver impressive bass, KR5 bass is simply outstanding. Think Odin bass but with bigger sub bass and a touch less control. And while Odin bass remains contained at all times, KR5 knows how to reach deep and slam hard when needed. EDM on this set is a club experience and will make your head shake.

KR5 bass also has a very tactile quality to it and will make your ears vibrate. A very satisfying experience. I liked that the bass also knows when step back when not called for. It feels clean and is never overpowering.

Given my personal preferences, I did EQ mid bass a touch down. A 1.5db reduction at 200hz does the trick. It improves clarity without taking anything away from the sumptuous bass.

Male Vocals surprised me on the KR5. While the graph implies a V-shape signature, male vocals came out pristine, emotional and textured. This set will satisfy bass lovers but also people who are looking for a natural and rich mid-range reproduction.

Female vocals can be a bit more problematic depending on source. And this is where my main gripe with the KR5 lies.

As you can see from the graph, there’s a peak around 9-10khz that can cause sibilance with some tracks. Pharrell Williams’ voice in “Get Lucky” sounded a bit peaky and so did Alexis Cole in “East of the Sun”. On the other hand, Billie Eilish recordings sounded incredible as she tends to stay in lower registers.

There are three ways to address this: a little EQ, tip rolling, and sources.

The last two are important with any iem. It is certainly the case here. To my ears, the KR5 pairs really well with sources that have smooth treble or even a slight treble roll off. The Sedna Xelastecs helped too.

KR5 technicalities are spectacular. The stage is the biggest and most open of any iem I have ever tried. Except maybe the MMR Thummim, but tuning is better here. It flirts with open HPs territory.

Dynamics are excellent. Imaging, separation and layering are as good as it gets. This is a technical set and will satisfy those looking for a detailed yet musical sound.  

To conclude, the KR5 is certainly one of the best iems I have ever had the pleasure to try. It will satisfy bassheads and people looking for a very big stage. An audition is highly recommended if you are treble sensitive and don’t want to use EQ.