JM Audio OpusX (50mm Biodynamic Closed Backs)

Introduction

Many of us have come to know John Massaria, either from the custom modded version of the Kennerton Gjallahorn JM Edition or more recently, the closed back Hifiman dynamic driver offerings including the Drop HE-R7DX and Sony/Fostex inspired HE-R9.

John and I are both based out of New York, so when he asked if I wanted to hear his latest mod, I immediately took him up on the offer. Having previously owned and thoroughly enjoyed the R7DX JM Mod, what I was expecting was another Hifiman… but what I received was something I haven’t seen from John before.

Packaging and Presentation

John clearly doesn’t lack personality or a sense of humor. I watched in my doorbell cam as the mail carrier put this package on my front stoop, then he stood there are stared at it for a solid minute before chuckling and turning to walk away. The outside of the shipping box was covered in waifus… top of the box, waifu. Bottom, waifu. Left, right, YOU get a waifu and YOU get a waifu.

Opening the box was inception. Foam outside bubble wrap outside shrink wrap outside a small pelican case. I opened it up and, gasp! …more bubble wrap outside headphones. But beyond the bubble, what I found wasn’t another dynamic driver Hifiman… cause who would go to such lengths to protect an R10D?

What I found instead were these metallic finished dark grey wooden cups, sporting dual entry flush mounted 3.5 jacks, housing 50mm bio cellulose drivers, damped and meshed like only John can do. And I knew why he sent these to me, because I’ve been on the quest to find the best bio driver (for me), having owned the E-mu Teak, Fostex TR-X00 (Ebony & Mahogany), TH610, TH900mk2 (Red & Pearl), Ultrasone Edition Eleven, and the Denon D5200, D7200, and D9200—the last one being my favorite.

No, it’s not another Hifiman. John calls these the OpusX.



Build Quality

When you hold these in hand, there’s a heft and quality build feeling to them. As I mentioned, the cups are a metallic grey paint over solid wood. The finish is beautiful, especially in the right light. They’re not perfect—it’s clear that these are handmade… a labor of love. There’s no factory churning out pieces of plastic with the awful timbral characteristics that sometimes go along with them. But while the imperfections are there, they’re very minor and certainly don’t impact the overall feel or presentation.



The headband is equally robust, but this appears to be the off-the-shelf universal headband you can find on eBay or AliExpress. Cups swivel but don’t rotate (much) in this frame, but I found it to be a non-issue. The adjustment clicks with marked detents so you can set them to your preference and return to that sizing whenever you need. And the headband strap is comfortable with no hotspots, though it flops down when you take the headphones off… a minor nit.

The sound is easily tweaked with pads but the headphones use a system similar to ZMF cans with a groove for the pads to sit in, except without the notch found on ZMFs. Because of that, rolling takes a little time and patience. John includes your choice of pads, and I’ve heard his fluffy ones and protein leather. John’s fluffy earpads are the most comfortable, like little puppies. Puppies that grab onto the sides of your head and fill your ears with joy (note to self: reword to be less beastial). They appear to be foam filled and compress well, providing an excellent amount of comfort and making clamp a non-issue. The pleather pads brighten the headphones up a little but are less comfortable. Clamp is not particularly strong but the headphones stay in place, and between the pads and headband strap, comfort is a non-issue despite the 457g weight.

Sound

If you skipped to this part, just know that I’d do the same. Like I said, these are 50mm bio cellulose drivers, modded by John.



Bass

Enjoyed: Talking Body (Tove Lo), The Greatest (Sia), HUMBLE. (Kendrick Lamar), Alone (Marshmello), Shivers (Ed Sheeran), First Class (Jack Harlow), redruM (Sorana), White Room (Cream), Sultans of Swing (Dire Straits), Starboy (The Weeknd), Tuesday (Burak Yeter), How We Do (50 Cent, The Game), Da Rockwilder (Method Man, Redman), Bullet with Butterfly Wings (Smashing Pumpkins), Sober (Tool), Rise (Jonas Blue, Jack & Jack)

Rejoice, bass lovers... these are elevated and they can hit HARD with EQ. The low end is very focused, and the bass response is more punchy and less bloated. But that’s not to say it isn’t full: the bass quantity on these easily outperform the Denon D9200 and TH610, but don’t have quite the impact or visceral slam of an EQ’d TH900. The 9200 has better bass texture and though I don’t own them anymore, the low end here reminds me more of the E-mu Teak than the TH900. Sub bass extends well with authoritative rumble when called for and mid bass creeps into the lower mids, creating a fullness and warmth that make for an enjoyable and fun listen. The bass here does have some detail, but it’s not overly done. I EQ’s these a little with the Lokius with great results—cutting the lower frequencies brings more detail, and bumping them creates almost no distortion but gives that impact many of us enjoy. If you love bass (as I do), these should make all but the most extreme basshead content.



Mids

Enjoyed: Shut Up and Dance (Walk the Moon), Senorita (Camila Cabello), Physical (Dua Lipa), Close Your Eyes (KSHMR), Listen to the Music (Doobie Brothers), Hold the Line (Toto), Rhiannon (Fleetwood Mac), National Anthem (Lana Del Rey), Eye in the Sky (Alan Parsons Project), Soul Survivor (Akon, Jeezy), Breed (Nirvana), Buddy Holly (Weezer), Enjoy the Silence (Depeche Mode), Remind Me to Forget (Kygo, Miguel)

Because the lows extend into the mids, some clarity and resolve is traded for a more fun and engaging listening experience. These lean on the darker side with both of these pads, not like a Denon D7200, and detail here is also more apparent than with the Denon. However, it’s again easily brought out with a small bump in EQ. Despite the warmth, I became accustomed to the stock sound after 30 minutes or so of listening, and afterwards thoroughly enjoyed the overall sound signature.



Treble

Enjoyed: We Were Young (PRIZM), Headlights (Alan Walker), Oye Como Va (Santana), Hold Me Now (Thompson Twins), I Want You to Know (ZEDD), It Ain’t Me (Kygo, Selena Gomez), Chief Rocka (LOTU), Get Me Home (Foxy Brown), Paranoid Android (Radiohead), Sabotage (Beastie Boys), Jeremy (Pearl Jam), Missing (Everything But the Girl), Hello World (Alan Walker), Big Energy (Latto), How Long (Tove Lo), I Miss You (Clean Bandit, Julia Michaels)

These custom cans by JM have a good sense of air. Treble sparkles some without ever becoming harsh, and I could detect no sibilance on anything I listened to, unlike the TH900. Resolving, yes, but they don’t pull every nuanced detail out from tracks. That’s not what these seem to be made for. They’re a more relaxed listen over a glass of your favorite Jolly Rancher Zima… I don’t know what the kids are drinking these days. The mesh John uses likely leads to more natural sound characteristics, creating tiny reflections and refractions in the upper frequencies. Coupled with the bio drivers, you get a natural and relaxed experience, with enough detail to keep you engaged. These drivers are also fast… maybe not planar fast, but dynamics are excellent, even on complicated tracks.



Soundstage & Imaging

Enjoyed: Dance the Night Away (Van Halen), Magic (The Cars), Lights (Journey), Head Over Heels (Tears for Fears), Baba O’Riley (The Who), The Chain (Fleetwood Mac), The Boxer (Simon & Garfunkel), Crying in the Club (Camila Cabello), Been Caught Stealing (Jane’s Addiction), Losing My Religion (R.E.M.), Bitter Sweet Symphony (The Verve), No Rain (Blind Melon), Linger (Cranberries), The Motto (Ava Max), All Night (PRIZM)

The soundstage is somewhere in between the TH900 (wide) and D9200 (narrow). But there’s a beautiful reverb you can just ever so slightly hear on the wooden cups which adds to the sense of space, and something you can only get on a good closed back. Imaging is very good with the placement of instruments easy to discern and believable. Vocals and instruments sound natural despite the slight warmth. Guitars and stringed instruments, in particular, are just incredible on these. And while I don’t listen to a ton of jazz or classical, these do really, really well for those genres.



Gear Used

Audirvana & FLAC on an Asus ROG Strix Scar (USB) > Audio-GD DI-20HE DDC (AES) > Sonnet Morpheus R2R NOS DAC (XLR) > Schiit Lokius > iFi Pro iCAN Signature & Ampsandsound Kenzie OG Rev 2

With both the iCAN Pro and Kenzie, these were black with no hiss or hum. Both amps were able to drive them really well but they benefitted from more power and scaled accordingly, especially the low end. I wouldn’t recommend these for low listening levels, despite their relaxed nature. Give them more power and they come alive!



Summary

TL;DR – these are bassy, darker sounding, and the treble doesn’t fatigue. With EQ, the low end can hit hard and they can be made more sparkly. If you’re a fan of the bio sound, as I am, these are worth a listen. They don’t slam as hard as a TH900 or are as full across the FR as the D9200, but they’re an excellent compromise between the two. A step up from the D7200, which also leans dark and has more rolled off treble. And an bigger step up from the E-mu Teak, where the mids are more recessed. The OpusX takes some of the best characteristics from all of these headphones and becomes its own special and unique creation.

John has told me that he’s going to focus on his next headphone, the XTC. So this OpusX is a limited run at the moment with only two more available at $699 in the leather tobacco matte finish. That will get you the headphones, pelican case, and your choice of earpad and cable (from two options each). John is also able to tweak the sound signature to better suit your preference (e.g. less bass, more detail, etc.) This color shift version would have to be special ordered and takes longer to make. They’re fun and worth a listen. If you're interested, you can contact @John Massaria here on Head-Fi.