Sent my Kennerton Gjallarhorn JM Editions into
@John Massaria, the guy who designed the original JM for Kennerton, to give them the full upgrade to the JM Edition MK2. Here is his website:
https://www.jmaudioeditions.com/
The mod really just awakens these headphones. Basically it takes everything about the headphones and turns it up to 11, bass gets turned to 11.5-12. Everything is just a little bigger and bolder with more snap and punch behind it. The Headphones are still a little
The mod takes the already stellar sound stage of the JM and makes it even big with out adding any hollowness/airiness to the sound. I would say the MK2 might even be getting into the HD800/Rognir sound stage range, especially if you are using the fuzzy pads John sells. The sound stage is at its most impressive during live recordings. It is almost like you are sitting in the audience and the band in playing in front of you and you pick out where each instrument is one the stage. I can not over state how incredible the sound stage is on these headphones. Not just for a closed back but even for the $1700(for the stabilized wood version $1500 for non stabilized wood version) John is selling them for ($175 for the mod if you already own the Gjallerhorn GH50/JM.)
I have yet to find a sound that these headphones couldn't handle. Never once I have I noticed any details missing or any song feeling crowded or congested like what can happen with some closed back headphones. Every detail is exactly where it should be nothing is missing from any song.
The highs are super clean and pleasant. Cymbals and percussion really have a fantastic and snap followed by a great ring/sizzle that is not fatiguing or lacking in any way. I can't imagine anyone would find the highs lacking or under developed.
Bass is one of the main things that is changed on the mod. The bass is just as tight and controlled as the stock JM but it adds more impact and power behind it. With out adding so much that it becomes over bearing or bloated. There is no bleed into the mids and It also slightly increases the bass speed and its accuracy with in the sound stage. I could see that some people might find the bass to be a little to powerful especially if you are comping from a headphone like the HD800s or any highs focused headphones. Just give your ears some time to adjust and you will find that the bass is the perfect mix of power and control.
The mids are lush and silky giving the headphones a warm and comforting sound that is hard to beat when it comes to long listening sessions.
Plugging the bass ports really brings the bass power down from a 12 to more like 10.5.
With the bass ports unplugged the bass in really front and center and the star of the show. It is just so impressive and fun that you tend to lose track of everything else because you are too busy jamming out to music.
With the ports plugged everything else gets a chance to shine. It lets the highs and sound stage get more of the attention while the bass play backup in a very pleasant non intrusive way.
Adding the ports almost makes the MK2 a 2-for-1 headphone with how drastically it changes the primary focus of the sound.
The only real complaint I have is that adding the bass port does slightly remove some of the isolation on the headphones allowing a little more outside noise to get in than over the stock JM.
Looking from the out side you can see that he changed a couple of things over the stock JM Editions. He removed the black felt covering the driver and replaced the Driver guard with a 3D printed mesh diffusion grid. So you do have to be careful not to get any dust or dirt into the drivers if you are using the stock pads. He added a Bass port on the back that can be plugged to reduce the bass. Looking into the bass port you can see that he added the same 3D mess to the back of the driver and changed the the dampening to his own custom material.
You can really tell that the MK2 is what the JM is meant to be.
