Kennerton Gjallarhorn GH50 JM Edition Mk2

John Massaria is like a mad scientist going to work in his lab creating the next Frankenstein monster; only this is not his day job; it is his passion.

John has taken his hobby to the next level. He loves to mod Kennerton Audio headphones, namely the Gjallarhorn GH50. So Kennerton decided to name a headphone after his mod and offer a GH50 JM Edition.

As any self-respecting mad scientist would do, John didn’t rest on the original mod and kicked that up a notch to the next level by developing the Mk2.

When I purchased my GH50 Limited JM Edition, I thought I would send this to John for the next-level spa treatment regardless of the out-of-the-box sound. I introduced the out of box JM Edition here.

To learn more about these mods, I include some links with more detail than you will probably ever want about the subject.

Mods 1

Mods 2


With these mods, I can only show you what is evident from the outside. Thankfully, my headband received an upgrade. The GH50 needs a tight seal to produce the level of bass the GH50 is known for. With the original headband, one had to contend with bending the metal arches to find the perfect clamping force to find the correct seal. This process was time-consuming, but my thumbs also needed a break. With the upgraded headband, bending is gone. Hallelujah!

The other visible mod is to replace the original acoustic fabric with the mesh fabric seen in the photos. John says that this allows for more spacious sound instead of the deadening effect of some materials, such as the OG GH50 have.

These are the visually apparent changes in John’s words, but the real magic occurs inside the cup and the mods there. I will trust his words and my ears for this. I am not going to disassemble the headphone to verify anything.

The OG pads on my Baltic Sea version from Audio46 were high quality. Very comfortable for short listening sessions or long listening sessions. They would collapse with a bit of time, and John added a lifter in the earpad to stop this collapsing from happening. Fortunately, the mod did not diminish my comfort, and the lifter has succeeded in its purpose. The pad doesn’t collapse.

Before moving to the sound, if you have any questions regarding mods or the pricing for this spa session, please reach out to John Massaria directly on Head-Fi and shoot him a PM. He is very accessible and a great guy.

Overall sound is incredible! Let’s start with the bass. In the OG JM Edition, the bass quantity was impressive, and the quality was average. I enjoyed the OG sound as far as a signature is concerned, but technically and critically listening, you could hear that there is a little room for improvement. The bass now has quantity, but also there is a better definition and clarity.

After this mod, Stanley Clarke 1,2 To the Bass and Marcus Miller Trip Trap will showcase just how capable the bass is. You can feel the bass and yet still hear the layers in the tracks. Trip Trap gives me goose flesh when I listen to it. If you are not into Jazz, try Infected Mushroom Never Mind.

The GH50 may be one of those headphones; at first listen, it makes you think that there is way too much bass quantity. It is especially true if coming from a high-resolution headphone such as the Denon D9200, which I reviewed here. It is an excellent idea to give any IEM or headphones a chance for your brain to adjust to the sound. I am not saying that these are not bassy headphones; I am saying that the mod cleans up the bass.

Fatiguing sound, not with this headphone. The more details you throw at the modded GH50, the more you will be rewarded. You will never hear any shrillness or disturbing treble artifacts. Cymbals and percussion are alive, which is also the name of a track I would recommend demonstrating how good they sound. Hiromi Alive is the title track on the release by the same name. I love the entire release and the trio; they are incredible musicians.

One of the most impressive features post-mod is the amount of stage. Pre-surgery, the width is above average for a closed-back headphone and one of its best features. Post-mod, the sound stage has increased not only in width but also in depth. I listened to Jean Michel Jarre Equinox, and notes were swirling around me. This is one of the best stages I have heard on a closed-back headphone.

I have been pairing the GH50 with the Cayin N8ii. There is plenty of authority and details for the GH50, and excellent pairing.

This writing is not a review of the GH50 or John Massaria. Instead, it is impressions and praise. Praise for the GH50 JM Edition and higher credit for the Mk2 mods.

I love these headphones! Thank you, John.