ZMF Eikon Review (Alternate Perspective)

A few months ago, I asked Zach Mehrbach of ZMF Headphones if it would be possible for both Amar and me to review the Eikon and Atticus, as we have quite different tastes so I was curious to see how our opinions of the two differed, and Zach graciously obliged. Amar published his reviews for the Atticus and Eikon a while ago.

Full disclosure: I’ve known Zach Mehrbach for years; I bought his original Fostex T50RP mods back in 2012 or 2013 and I’m astounded at how far he’s gotten in such a short amount of time. I’d consider him a friend at this point, but I don’t believe I feel any overwhelming bias. I had the chance to buy the Eikon or Atticus at a discount but as of now have no plans to take advantage of it.

The ZMF Eikon is a far cry from ZMF’s older T50RP mods which use a T50RP headband. The T50RP headband is durable but in the case of the Ori, doesn’t really seem fitting for what it costs. The Eikon, however uses a frame that seems much more “premium.” It’s quite obviously inspired by the Sony R10/CD3000 but feels much more robust than my CD3000. It’s made entirely of metal and feels quite sturdy but the frame does seem to add weight to what is already a conceptually heavy headphone due to its very thick wooden cups. My only major complaint about the build is that the adjustment rods spin freely and when I take off the headphones or pick them up, I need to make sure the cups don’t knock into each other.

I’ve heard the Eikon numerous times before having a long term loaner so I felt like I knew what to expect, but oddly, each system with the Eikon was like a different experience, especially out of meet settings. I mainly used them out of my Theta DS Pro Progeny and Krell KSA-5 Klone and found their upper midrange between 1-2kHz to be slightly distant. Bizarrely, out of a Schiit Fulla 2, the distance was slightly lessened, enough that I found myself complaining about it less and used the combo almost as often as the Theta and Klone. I actually did an informal ABX test with a Schiit Sys (when I say informal, I mean it; I took two computers, had them play the same file at the same time, and clicked the button an arbitrary number of times really quickly) and while I obviously cannot make conclusions without conducting a formal test, the differences I did notice and the degree to which I noticed them made me curious enough to possibly attempt a legitimate test in the future because I actually sound myself to prefer the significantly cheaper setup during the testing.

Overall, the Eikon sounds warm, but with unevenness in the upper midrange. The most interesting thing about the Eikon is that it uses a biocellulose diaphragm, which is something only Sony and Fostex (and by association, Audioquest, Creative Labs, Denon, EMU, and ENIGMAcoustics) have previously used in full sized headphones. This driver appears to be unrelated to the Fostex biocellulose drivers that many other companies use, so ZMF has much to prove with their first nontraditional design, and in many ways they do succeed. They’re a very pleasant headphone to listen with, but they’re not without quirks.


When most enthusiasts think of biocellulose headphones, they imagine the hard-hitting bass of the Fostex TH900 or TH-X00. Interestingly, the Eikon doesn’t hit like a Fostex-designed biocellulose driver. These seem to focus more on rumble than slam, which is a characteristic that is typically attributed to planar magnetic headphones, so I found it especially interesting that the Eikon is legitimately adept at creating a sense of sub bass. They still slam rather hard, certainly much more than most planar headphones, but switching between an Eikon and a TH-X00 may take a couple minutes to adjust. I’d personally like a little less bass than these produce because the elevation combined with the slight slowness to the bass can almost make them sound congested with complicated music. It’s cleaner and clearer than the Atticus and Sony Z1R, but the balance can make simple acoustic guitar pieces sound slightly off balance.


The ZMF “house sound” seems to consistently pay special care to midrange; the Eikon is no exception, but there are a few oddities I noticed.  Unlike past ZMF headphones, the Eikon doesn’t lack low midrange—it’s actually pretty even. I do have a couple problems with the midrange though. There’s a noticeable dip-spike between 1-2kHz that gives off a sort of distant feeling but also brings guitar attack forward, and is followed by a bit of a rise in the upper mids around 4kHz that makes female vocals sound slightly nasal and more forward. It’s not the worst thing, and certainly less annoying than the Sony Z1R’s occasional telephone-like tonality, but it does sound rather unnatural. I’m actually slightly reminded of the Audio Technica AD2000, which is one of my favorite headphones for female vocals, full stop. It’s less forward and better integrated with the sound than the AD2000 though. The strange midrange balance also does wonders for acoustic guitar; the dips and bumps flatter and push the guitars forward. It’s not an accurate or natural presentation by any means, but it just works for me. I can definitely see it being hit or miss with others though.


I wish these had more treble. Low treble never leaves me wanting extra presence, but upper treble and mid treble left a bit to be desired. I occasionally felt the Eikon sounded congested because of the roll off that occurred past the low treble. I’m glad the Eikon doesn’t have the 10kHz peak many other headphones have because I was able to use the Eikon for over ten hours at a time due to a complete lack of fatigue, but I found myself wanting a bit more aggression and air at times.

Alternate Pads

I was able to try the Eikon with both Ori pads in addition to the Eikon pads. The Ori pads sealed a bit too well for me (I had an almost vacuum-like seal) so my experience may not be indicative to actual experiences. I wasn’t a huge fan of the Ori pads on the Eikon. The main difference was added extra midbass, which I really don’t think the Eikon needs, and a bit of 10k which, I guess, makes them more “normal.” I also tried Brainwavz HM5 hybrids with the Eikon. It added a little bit of nasality to the sound and some sibilance, which I could definitely do without.


I messed up; I forgot to take multiple positions before sending them back. I hated measuring the Eikon and Atticus because of how the pads interact with my coupler. Just the slightest movement would change something be a couple dB. This result is the most consistent though. The strangest thing about the measurement seems to be the divot at 1.7kHz. I asked Zach about it and I believe he said it was due to resonance, which I think would lead to high distortion that I expected to hear but surprisingly didn’t. The dipspike is there and audible though, as is the rise at around 4kHz. Unsurprisingly, the Eikon dips past 8kHz which is in line with my subjective thoughts in hearing them as relaxed.

Green is Ori pads, pink is Eikon pads, purple is HM5 Hybrid pads. The Ori pads clearly are the bassiest of the three, possibly because they sealed so well. They also are the only pads that introduced a mid treble peak. The HM5 Hybrid pads do show more presence in the low treble and 7-8k sibilance region.


The ZMF Eikon was a bold move; after working with T50RP drivers for so long, creating a flagship headphone, especially a closed one, with a new, unproven, driver is a huge gamble. The ZMF sound historically has never leaned towards “neutral” and I’m glad the Eikon doesn’t attempt to be such. Instead, the Eikon is unique; it offers a kind of sound that I legitimately can’t compare well to other headphones because it seems to be tuned towards flattering music rather than measuring well. I can’t say it works one hundred percent of the time though, as its coloration can get rather distracting when I’m not in the mood for it. But what surprised me most is that during my time with the Eikon, I never thought it was, “good for a closed headphone,” and instead, thought, “this is a good headphone.” It’s definitely not a sound that will work with everyone, but I’ve yet to hear a better love letter to simply enjoying music for what it is rather than “how it should be heard” than the Eikon.