Reviews By Wave Theory
Review on Stock R9 vs R9 JM Audio V8
Hifiman HE-R7DX JM Edition
at about 13mins in- Michael De Lazzer a two-time Emmy® Award winning producer and owner of The Directors Garage
ardbeg1975 said: I also just got back my GH upgraded to “Mk2” by @John Massaria whom I’d also like to personally thank for his sonic surgery. I’ve been listening to the Mk2 for the past day and I’m very impressed particularly in comparison with my VCs. I’ve been running the Mk2 and the VC on a Tor Audio Balanced transformer coupled tube amp (1980s-era Soviet tubes) and a Flux FA-22 SS amp, both fed by an up-sampled 8X stream from Qobuz via Roon to HQPlayer to Zen Stream to Qutest. Bass — Just Awesome. The bass on the JM edition was already very enjoyable but I echo the earlier comments that the imaging and sound staging are improved over the original. The VCs are still more visceral but the Mk2 seems to perfectly capture the middle ground of the bass presence and dynamic rumble of the VC and the imaging / separation precision and control of the Rögnir. Kick drums in particular are just great. Midrange — I dare say Mk2 is giving the VC a contest here as well. VCs may still be a touch better in timbre but particularly on the Flux, the Mk2 is exceeding the VC in depth of sound-stage for the vocals so it may come down to whether you prefer that “closer to the stage/vocalist” feel or not. I give the Mk2 the edge in vocal imaging and separation precision on many of the tracks with which I tested. The two HPs are trading blows depending on the track in width of sound stage. I may give the Mk2 the slight win in pure width but the VC the win in holographic effect. Call it a tie overall. (Side note — I took the extremes and tested with High on Fire’s Art of Self Defense, a very sludgy album, and with Khruangbin’s Con Todo El Mundo, a very articulated album.) Treble — Smooth and non-fatiguing on both the Mk2 and VC. I’d give the VCs the edge here in timbre and detail retrieval, particularly on the metallic reverb of cymbals, but not by much. Overall, the GH JM Mk2 is holding its own against one of the best closed back dynamics in the VCs and doing so at circa half the price. @John Massaria you aren’t charging enough for this mod.

First off, If you are looking for a set of closed back headphones in the sub the sub $750 range, look no further than these headphones. They are incredible and out preform many of the closed backs I've tried that cost 2-4 times as much. Seriously, try these headphone you won't be disappointed.
I have the new version of the mod, the Bass+ version. Which adds a bit more emphasis to the bass over the base mod.
I first heard of the JM Edition from @John Massaria when I was having him mod some other headphones I own. He is a great and trust worthy guy who is super passionate about his mods and takes great care in modding headphones. (READ MORE)

"GH50 JM Edition Gjallarhorns did one of the best jobs I’ve ever heard from a closed back headphone." - Headphone Dungeon

gadus said:
I bought them (r7 jm mod) and I'm very pleased, their sound convinces you that the music is right in your room, they easily sound like $ 1000 or more headphones, Thanks John!
In fact, if you calculate price and value, this is one of my best purchases this year, and I had much more expensive purchases ...I also wrote a review here on the site, the truth is I have a lot more words in my stomach but I am less good at writing ...
(Location: Israel drop shipped from USA)
REVIEW OF HE-R7DX JM OCD
EXTREME STEALTH + BASS EDITION"SETTING A NEW STANDARD IN CLOSED BACKS."
FIVE OUT OF FIVE STARS -LICKUMMS HEAD-FIER

"Originals do not come close to the modded....
If I could use an analogy, imagine watching a movie on a flat screen (original) vs watching it in 3d in IMAX (modded R9). You’re able to perceived things and almost “touch the sound”, this is a quality that is present in top tier headphones... Modded R9 is more punchy overall, speedier... Timbre on the original is not very accurate, on the modded ones they are very accurate. If there are 10 different drums used in a song, you will be able to pick out the 10 slight differences on the modded R9."
REGARDING GH50 JM MK2 UPGRADE
After I shipped back the newly modded JMk2 back to the owner I was concerned so I wrote- "If you aren’t amazed on the mod send em back I’ll do what ever to try to make it how you like"
The new owner of the Mk2 said: "I don’t think that I will be sending them back! The soundscape and layering remind me of those of ZMF Atrium! And these are closed-backs! amazing! listening: fantastic! The virtues of the pre-modded GH50 JME with added strengths !! I will be commenting in the Kennerton thread with more crystalline observations " - jonathan c

A lot of people ask, "What's the turn around time for JM Fractal total mod?" the answer: typically a day or two ...
just email me it's easy! massariaj@yahoo.com
I hope you give me chance! -JM