Hifiman HE-R9 JM OCD Extreme Edition

General Information


Modification of the Hifiman HE-R9 by John Massaria.

  • Frequency Response of 15–35 kHz
  • Impedance of 32 ohm
  • Sensitivity of 100 dB
  • Weight 328g
Important to note that internal wiring of 3.5mm port to driver has been modified; thereby rendering the bluetooth dongle unusable.

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New Head-Fier
At The Cost What's Not To Love?
Pros: Soundstage For Days
Clean Textured Bass
Nice Bass Shelf
Natural Midrange
Non-Fatiguing Highs
Play Well With Tubes
Cons: Can't take them for a walk
My Background: In Case Context Is Important To You
You can skip this if you'd like but given that this is my first review, actually my first anything on head-fi, I feel that it's important to provide context on my observations based on my experiences. First, I'm a storyteller by nature and am typically verbose, I apologize :p. Also, I would like to note that these are my own thoughts and experiences with these cans, which I've had for about two weeks, in no way have I been incentivized to write this review. I just noticed how few reviews, one at the time of writing, this sleeper had and thought I'd give a crack at it as my first post here on Head-Fi.

The Beginning: I've been interested in music and been messing with stereos since I was a kid, I helped my mother setup our Bose LifeStyle 12 II in our small den when I was 9. While I know better now, at the time it was a massive improvement over the little crt's stereo that we had going originally. For all its faults, which were many, it had an excellent diffused sound stage and with that I became interested in surround sound in general. I tweaked that system till I started building my own in my small bedroom, my family was big on garage sailing and from that I built my first setup from a mishmash of speakers and electronics. At that time I didn't really know what I was doing but I was becoming more discerning and informed. The best thing that came out of that was my "discrete" subwoofer system, a neighbor had thrown out a pair of JVC tower speakers as he had blown out everything but the woofers. Limited by my small room I cleaned out the bed's trundle and placed them both under my bed and let me tell you they were thunderous and a heck of a lot of fun. I still have those towers in storage if I ever manage to get out of living in apartments.

College: When I moved out I brought most of my system with me and I was extremely lucky that my apartment was right next to Salvation Army that was a boutique-ish store in that they had a constant hi-fi selection for absurdly low prices. I got to try out, refurbish and resell a bunch of equipment that I otherwise would never have gotten to try. Before I settled on my "endgame" in that apartment, I managed to get myself a 9.2.2 system. Used to have weekly get togethers where my friends would gather in my apartment to watch the movie of the week and such.

DIY: Through that SA I came across a pair of Super Rhino cabinets, can't find much on the internet anymore but they were these MASSIVE wood cabinets with dual 8 woofers, a Philips "egg" tweeter and midrange. I had done some restoration work but these guys needed some help and so I reached out to a friend's father who I convinced me to rebuild them in it's entirety. Two years later they lived as an completely different beast, a 3 way active design that utilized the vintage amps I had collected. I downsized my setup to a 5.2.2 to simplify, cut down on heat and electricity, those towers were literally life changing as the amount of research and time that I put into their design helped to form my understanding of what a truly good sound system could be. The sad part is I moved out 6 months later and they've been in storage since as my living space over the years continually becomes smaller and smaller.

DIY 2 Electric Boogaloo: Gonna make this a bit brief, I moved to a different state for work my new apartment was too small for a theater in my bedroom. I spent another couple of years researching and saving for my next build. I've built a nearfield active 4 way in a desktop form factor. They are tuned to have a wide soundstage with a relaxed but detailed sound signature. I could review it but that's not why we are here (emoji insert)I've moved since and they were able to move with me to where I'm currently living somewhere even smaller, with roommates.

Headphones: Finally! We are in the present! Up until a couple of months ago I've only had a little bit of experience with headphones with the exception of my Sony WH-900N H.ear on 2 which has been with me since 2018 I believe which also is my only comparable closed back headphone. There's also the Dekoni Blue which is semi-closed... frankly I dislike them. I do have a small choice of open back for comparison; Grado Hemp w/Pad Roll, Beyerdynamic T2.2, Thieaudio Ghost. As such I won't make any comparisons between these.

TLDR; All of this preamble is simply to state that my experience with audio has mostly been with stereo and surround systems and not with headphones. Onto the Actual Review!!!

Build and Comfort: Boring But Important Nonetheless
One of the many benefits of JM Audio is that they offer customization options for their headphones, I was able to choose between two headbands and I went with the Enhanced Arya Style Headband. The original fit was a bit too tight and put pressure on my temples after about two hours of wear, I must note that I wear glasses which I believe played a factor in this discomfort as well. Luckily the headband is easy to adjust, using a little bit of pressure I loosened the headband to where it's comfortable for many hours without discomfort. With the headband at its stock position, I had the notion that these were heavy and fatiguing cans but once adjusted they feel light and comfortable thanks to the suspension style headband. The cups themselves are tad bit cumbersome, I don't think anyone would recomend these for travel simply because of how big the cans are, that being said I'm quite partial to the function over form plus I know that the design is inspired by Sony's MDR-R10. The cans themselves are interesting in that if you do a finger rasp test on them, they do have a nice deadened sound to them which likely has to do with JM Audio Proprietary Fractal Mesh Technology™ and Fractal Fiberglass Porous Carbon™, very cool stuff. The pads are stock Hifiman, plenty comfortable if not a little warm after a bit but I think that's to be expected of a closed headphone. This all is a wonderful thing as I need them to be comfy for long sitting hours as I'm a work from home IT manager and my roommate is constantly on calls which leads me into the next section.

Isolation: Closed Back Cans Can Do The Can Can
I imagine most people get closed backs for the sake of isolation, working in a noisy environment, traveling, etc. These handle sound isolation well for my use case, during work hours I can't hear my roomie and he can't hear me, that's all I could ask for.

Listening Gear: The All Important Source
First off, if you've read all of the above and are still with me, thank you! Running off of USB from my PC into the Geshelli J2 (Non-Socketed) and I tried the R9's with these amps: THX 789, NITSCH Piety and LD MKII with rolled tubes (Mullard M8100) and all three run these with next to no effort. For most of my my time with this review I listened through the Piety as enjoyed this combination plus it's my newest toy and I can't help but enjoy it :p. I don't have a traditional list of reference music, typically I just listen to whatever I'm enjoying at the time, if you really need a break down of my preferred music please ask me how x sounds in the comments section and I'll do my best to give a listen and provide my thoughts.

How Does It Sound? This Is What You're Here For Right?
Presentation: Wow, we finally made it and I don't mean to spoil the end but, these are some fine cans! At the time of writing this review, these are my favorite headphones and are now competing with my personal stereo for run time outside of work hours. Let me start off with the stand out of these cans and that's the sound stage. If you are aware of John and JM Audio prior to this review then this may not be much of a surprise but the claims that his product page makes for the R9s here (https://www.jmaudioeditions.com/product-page/hifiman-he-r9-jm-ocd-extreme-stealth-edition) are no joke, the sound stage is held in what I would describe as a medium sized room where the stage provides room for the instruments to breath and have their own space in the music, they are neither intimate nor distant. They are also rather dynamic which I think empowers them in their overall presentation. Combine this with clean imaging and instrument separation and you've got the makings of a real winner. Also, they are no slouch in locational accuracy, they are a fantastic companion for gaming sessions and you don't even need rgb!

Bass: The Bass is presented in a very clean fashion, at no point does the bass overwhelm the midrange or sound muddy. I wouldn't say they are bass cannons but the bass is definitely there! I'm more interested in the bass quality and the ability to resolve bass texture which is something that they do well. The ability to listen to the strings on a guitar being individually plucked and here them reverberate is a reality here which is something that is extremely hard to do. Something funny to note is that reverb as an effect is actually rather noticeable in a non-distracting but strangely observable in some music which I think has to do with that natural transient nature of the bass? If some here has a better way to describe this please lemme know!

Midrange: I could give it a three word review, Natural and Smooth. While these do have a good deal of detail and definition, the overall midrange presents itself as natural and smooth. It does a nice balancing act for the midrange as it neither adds nor detracts from the overall sound signature, neither super defined or laid back, for lack of better words I'd call it a faithful reproduction throughout the midrange. While some might prefer to have some flavoring in their midrange I think this is a strong base.

Treble: Enjoyable, non-fatiguing or piercing although at higher volumes it might catch you by surprise. This is perhaps the most uninteresting part of this review as I can't find any faults with the treble but it doesn't standout in any particular manner which perhaps is a good thing.

Tubes: While I did most of my listening on the piety, which is designed to be a tube-like solid state amp, I would like to note that, at least with my tube amp, these did play nicely with them and added a touch to the soundstage and made the treble and midrange a touch sweeter, your tubes may vary :wink:
Conclusion: The Ultimate TLDR;
I might've spoiled the conclusion at the beginning but I am thoroughly enjoying these headphones, if only they were made fashionable to walk the block with... hmmm, they could be considered a fashion statement? Seriously though, if you are in need of a great pair of closed backs for whatever reason and the price is right for you I would suggest you give these a try, if you don't like their initial tuning, it's advertised throughout the the product page that they can be further customized to your liking. If you aren't looking for a closed back for a particular reason but something fun and different to your collection I can also recommend these as the sound stage is not a gimmick, its not dsp or some snake oil, its real and its GREAT!

If you made it to the end of this, again... thank you very much and I apologize for any rambling or lack of clarity in my review, as this is my first review and I might write more in the future; any and all feedback is appreciated :)
K othic
K othic
Hey AetherDrive, nice review! I believe that for a first one you've made a really good job describing the different aspects of the sound signature. I am not really a stereo guy (more of a headphones/IEMs guy) so I'm not educated on stereo systems enough but I appreciate that you took time to explain where your experiences come from. I hope you keep writing and don't be afraid haha (I'm kind of new too so I know it can be a little scary). Cheers!
Hey K othic, thank you for the kind words! I was a bit worried that it might've come off as me talking more about myself so I'm glad you appreciated that bit and enjoyed my review :)


New Head-Fier
One of the best headphones I've ever heard
Pros: Emphasized bass that is controlled
Highly resolving
Exceptional soundstage and imaging
Inoffensive high frequency range for laid back listening
Comfortable for long listening sessions due to being well distributed
Cons: Unable to use bluetooth dongle due to modification
Weighs 328g, something to consider for those sensitive to weight


Before I begin I must first mention that I bought this headphone and was not asked to write or post a review. As such, these are my genuine thoughts.

The headphone I'm covering in this review is a modification of the Hifiman HE-R9 headphone that was released in China in November of 2021 and was made available in US markets in the early part of 2022. The HE-R9 is a deviation from the usual offerings that Hifiman provides due to it being a dynamic driver headphone as opposed to being planar magnetic drivers that consumers have come to expect. It should be noted that both the HE-R9 and its big brother--the HE-R10--are both homages to the Sony MDR-R10 which has developed a cult following due to both its scarcity and performance, propelling it to legendary status among audiophiles. I myself have not been lucky enough to hear this headphone in person, but the consensus among those who have had the opportunity--especially back when it was released--is that it pushed the envelope of what was thought possible in a closed back headphone.

While that information may seem inconsequential at first glance, I feel that it is a key reason as to why the modder decided on modifying both the Hifiman HE-R9 and the HE-R10. I feel that in his own way, he aspires to "extend the legacy" of the Sony MDR-R10 by continuing to push the envelope in closed-back headphones the same way its obvious inspiration did. Now the question is: did he succeed?

Build and Comfort:

There are no modifications to the build of the headphone itself so, in effect, I'm reviewing the stock HE-R9's comfort. I've heard people state that the earcups feel like cheap plastic, one head-fier going so far as to say that the earcups feel "egg-shell thin" but I disagree. These earcups feel sufficiently sturdy without feeling too thick or brittle. They feel like they would be able to sustain a fall if they accidentally fell off of your head; but I'm not going to test that theory. The headband construction of the HE-R9/R10 is shared by the DEVA series and is a clear step-up from other Hifiman headband setups that feel cheap and, quite honestly, disrespectful to the end consumer. I used to physically cringe whenever I had to adjust the headband because the quality control was inconsistent and, at times, the act of adjusting the headband would chip the paint on the metal.

Aside from being built better, the headband is actually fairly comfortable, it's pleather wrapped around memory foam, and should be comfortable for mutliple hour sessions for the general listener.

The articulation of the cups both of the X and Y axis is fairly limited, but the headband is pliable enough for it to not be detrimental. The clamp force is satisfactory, it isn't too forceful while not being too loose. The weight of the headphone is very well distributed and feels lighter than it really is. It's about 328g which is lighter than the Focal Elex at 450g but understandably heavier than the Sennheiser HD 6XX which clocks in at 260g.

Sound Isolation and Leakage:

Although this is a closed-back back headphone, the sound isolation leaves much to be desired. With no music playing, I would be able to fully engage in a conversation with someone else at normal distance/decibel levels. Ironically, the sound leakage isn't too bad; and the earcups do a fairly good job at containing the sound. I don't have the stock version of this headphone to compare it to, but the JM OCD Extreme Stealth's (what a mouthful) have the inside of the cups lined with "heavy duty heat resistant sound liner," which is probably reducing the sound leakage.

Technical Parameters:

John Massaria, the creator of the mod, differentiates himself from others by using what he calls a 'fiberglass fractal mesh' to aid in the acoustics. He provides a visual on his website <www.jmaudioeditions.com/innovations> which shows a simulated render of the effect the fractal mesh provides on 3 frequency bands: 100hz, 1000hz, and 4000hz. Of course, that isn't the only modification he performs, but it is upon this foundation that he builds a uniquely pleasant sound that I had never heard before in any other headphone.

Taken from the product page:

fiberglass multi-pattern actually helps bring all frequencies out and expand them...the pattern I created here actually de-accelerates the sound waves into a very spacious sound "meshing" unlike fabric which has a deadening narrowing...this mesh material tunes the sound waves and it comes alive due to their fractal nature- and allows pinpoint accuracy and a wider stage fooling the waves into a creating a larger than life pattern while minimizing any echo or ring in sound waves - it works better than fabric (the idea comes from using much more expensive porous/foamed aluminum similar to ones used on the back wave of the Abyss AB 1266 TC or the Meta Material used in front of the Dan Clark Stealth or the Meta material used in the KEF speakers)

Another modification which I greatly appreciated is the direct connection between the 3.5mm port and the drivers. The stock version of this headphone has an intermediary wire between the left 3.5mm port that splits between the driver and a wire that goes through the headband to the right cup driver. This is to support the bluetooth adapter accessory. However, the way the 3.5mm port was wired internally also meant that not all third party cables were compatible, it depended on how the cable was wired. John has removed that cable and wired the 3.5mm ports in both earcups to the drivers directly for better connectivity. As a caveat, this means the mod doesn't support the bluetooth adapter, so be aware of this important detail if you're considering this particular mod.

Aside from that here are some other technical specifications:

  • Frequency Response of 15–35 kHz
  • Impedance of 32 ohm which means it's easy to drive.
  • Sensitivity of 100 dB

Pre-amble to Subjective Sound:

For context on my methodology for this review:

1). I listened to the HD-6XX with ZMF Perforated Lambskin pads for a month prior to my first impressions.

I knew I was in the market for a new headphone and I also knew I wanted to make a review, so I decided to listen to my HD-6XX's for a "mental burn-in". I figured that by getting reacquainted with a headphone that many people are familiar with, I'd be able to easily tell what the difference between these two headphones and--hopefully--articulate the differences.

2). I listened to songs that I was very well acquainted with. This compounded with my first reason.

I will also be listening to this headphone through the Topping D50 + Massdrop THX AAA 789. This pairing, in my opinion, offers the best price to performance of any setup I've heard.
With that out of the way, let's get into the sound impressions.

Subjective Sound:

This headphone surprised me for many reasons. The first surprise was the bass. When I tell you the bass is phat I mean the bass is PHAT. I'm talkin' like morbidly obese levels of phat. But that isn't to say that the bass is loose, uncontrolled, or bloated. No, my friend, the reason this headphone surprised me is because despite having the heftiest bass I've ever heard in a headphone it still--through some magic--is able to present the bass in an articulate and refined manner with no compromises. This headphone has a commanding authority in the way it presents bass. I can't overstate how powerful it not only sounds, but feels. On a track like Lose Yourself to Dance by Daft Punk the bassline extends deep into sub-bass frequencies, providing a smooth rumble, and whenever the kick drum is hit there's a palpable mid-bass punch. In all honesty, the way the bass is presented is reminiscent of a good speaker setup; you not only hear it--you feel it.

The second thing that stood out to me was how well this headphone presented the mid-range and handled resolution/transient response. This headphone's transients are fast. I mentioned how this headphone is able to present bass in an articulate manner with no compromises, and I mean that. If you've fooled around with EQ and attempted to bass boost your headphones, you'll know firsthand that a bass boost has an impact on the mid-range. If you boost the bass too much you run the risk of "muddying the mid-range" where you start to lose resolution and transient response in vocals and instrumentation.

To illustrate how good at resolving/transient response this headphone is, in the BBC live recording of Valerie by Amy Winehouse I am able to hear the initial twang in every bass note that's played. I had never been able to hear that before, even on my Focal Elex's. To be honest, it took me by surprise. I didn't expect to be able to hear new things in recordings I'm so well acquainted with.

One of my favorite genres to dissect a headphone's presentation, oddly enough, is Afrobeat music. Reason being that it's fairly minimalist. There's a beat, there's a voice, but most importantly, the production quality is amazing. In Damages by Tems the first thing I noticed was that I could hear the texture in her voice much better than on the HD 6XX and the instances of scattered percussion sounded much more life-like. I could even hear her part her lips 10 seconds into the song.

Speaking of texture...

String instruments in particular have never sounded so good. The fretless family of string instruments (violin, viola, cello, etc.) have a wonderful texture when played with a bow. One string instrument in particular is notoriously difficult to get correct: the cello. The cello presents a particular challenge because it has a beautiful mid-range, but many headphones struggle with presenting the lower frequencies which leaves it feeling inorganic.

One by Apocalyptica is a cello only cover of the Metallica song by the same name. It's my go-to song when analyzing cello presentation. I'm looking for three things when I listen to this song:
(a). texture
(b). low end presence
(c). hidden details like the musicians accidentally hitting the handle of their bow against the cello which happens a lot towards the final portion of the song.

Most headphones check the box on one or two of those qualities but I'm happy to say that the JM OCD Extreme Stealth gets it right. The trifecta is all there. The texture, the lower frequency, and the detail; it genuinely sounds like I'm in a theatre listening to the performance which is hard to do. Since this headphone has a heavy focus on bass I was expecting this song in particular to sound "stuffy" and cramped, but that's not the case here. Instead it sounds open, to the point where I feel like I can visualize in my mind's eye the dimensions of the room they recorded the song in. This headphone gives a great impression of dimensionality which is a perfect segue into the next portion: soundstage.

The soundstage in this headphone is also unique. The only way I can describe it is by saying that the soundstage is genuine. What do I mean by that? I mean that the soundstage doesn't exaggerate a sense of space, nor does it feel confined in a box. Is the song recorded with the intention of conveying space? If it is then the soundstage is vast, if it's recorded intimately then the song will sound intimate. This is another quality that I haven't heard in a headphone before. It is because of that quality that I feel like this headphone can lend a different lens to view music with.

Consequently, the imaging on this headphone is amazing.

There's a wonderful country song that I love to listen to in order to get a good understanding of how different speakers or headphones present soundstage/imaging called Hold On by Amber Rubarth. The song features a number of instruments and I can pinpoint with precision where on the stage (or recording booth) the musicians are.

The last part of the frequency response range is the treble region, and what I can appreciate from the JM OCD Extreme Stealth's is that the treble is tame. At no point did the high-end sound sibilant or hot; I never felt the need to turn down the volume because of sibilance which is a common problem I have with most Hifiman headphones.


If I had to succinctly capture my thoughts on this headphone it would be as follows: "this is the sound signature I've always dreamed of."

I used to think that there's always a trade-off between bass and detail.

I used to think that you'll never find a headphone that has both booming bass, and silky smooth mid-range detail.

I used to.

What John Massaria has done here is remarkable. He's somehow been able to create something that confounds my understanding. This mod of the HE-R9 is one of, if not the most, fun headphone I have ever had the pleasure of listening to; and I've owned or had extended listening time with a decent number of good headphones such as
  • HD800's
  • HD6XX/600
  • Hifiman HE1000
  • Focal Clear/Elex
  • Modhouse Argon Mk3
  • ZMF Eikon
  • ZMF Atticus
So who is this headphone for? This headphone is clearly tailored to those who like an emphasis on bass, but I'd also argue that every audiophile should have at least one headphone or speaker setup that is "pure fun", even if you favor neutral or analytical sound signatures.

Because I've said so many positive things about this headphone I feel it necessary to mention that John has not asked me to write a review; I am doing so because I genuinely want others to experience his work.

Still, I want to say thankyou to John for making these headphones, your passion and dedication to the craft is astounding, and I will be keeping an eye out for any of your new projects.

Keep up the good work.