After my journey of gear cycling, I’ve basically accepted that no open back headphone fits me better than my trusty JAR650. However, as much as I love my 650s, sometimes I crave for that subbass and monster slam to blast me off into another dimension. Previously owning the Borealis gave me a taste of what good slam can sound like, but I wanted more.. This is where Evan’s ESX900 comes in. I’m not sure how useful my impressions will be since mine is slightly tuned differently with a one-off monkeypod wood cups that are slightly deeper than the typical Fostex cups, but I imagine most of its inherent technicalities will be similar to Evan’s original and upcoming pairs for the loaner tour. OK so how do they sound? Main Rig: Pi2AES > Sonic Frontiers SFD2 Mk.2 > DNA Starlett | BHA-1 > ESX900 | HD800 (SDR+SBAF Rugliner + Cork) portable/ other rigs: Macbook pro > ESX900, ES100 mk.2 > ESX900, iPhone 7? > apple dongle > ESX900 Tonally, it has some resemblance to Verite Closed, no joke, @ChaChaRealSmooth heard these briefly before me and we had similar thoughts regarding the tonality. Evan’s pair has a different set of pads than mine for a slightly more downsloping, smoother FR while my pair has the “pancake pads” that are flat, but very soft and pillowy. This is the measurement that Evan sent me as he was working on the mods. When I first got them from him, it sounded mostly fine, but it had a bit too much air for my taste and heard some sharpness in the vocals which kind of irked me. Evan then suggested that I put a strip of micropore tape across which surprisingly fixed the issue for me. I swear this dude is a wizard… wtf lol After the mods, I would say more or less that graph, but treble seemed a bit more in line and cohesive. I don’t have a VC on me, but I think a direct comparison between the two headphones would be a very interesting experiment. The shining quality of this headphone is the insane macrodynamics/slam. The bass impact is just so satisfying to “feel” especially after being accustomed to 650’s one note, wimpy bass. ESX900 has great macro contrast between the highs and lows, and I would describe them as authoritative, clean, grippy, and lively. I’m willing to bet that this might take the cake for best slam in dynamic driver headphones. I was a bit worried that the bass would be overwhelming and would make the rest of the FR feel disjointed, but it didn’t feel that way during my time with this. Evan’s able to tweak your pair to better match your preferences so if you find the original mod slightly bassy, maybe try it with the flat pads like my pair. TH900 drivers are surprisingly resolving once you fix the atrocious tuning of the stock headphones, that can portray nuance and microdetails well. Despite being extremely easy to drive, they do scale with better gear. I thought I would enjoy this more with BHA-1, but Starlett seemed to synergize better for some reason. Another cool aspect of this headphone is that it can be driven off of most portable sources, but can scale further if you choose to use it in your main rig. I tried it with both my main rig (SFD2 + Starlett) and some portable DAC/Amp (ES100 mk.2) and sources (macbook pro and apple dongle) Like the Auteur, I love the timbre of biocellulose drivers, I much prefer it to the faster, maybe more technically efficient beryllium/beryllium-coated drivers in the likes of Utopia and Verite. Instrument pitch and tonal characteristics sound righteous and natural with little coloration. Clarity is quite good, but it’s not the best I’ve heard compared to something like Utopia, SR1a, or HD800. Maybe it’s the upper mid depression/lacking a bit of presence that you see in the graph, or maybe my ears are just used to the 6x0 signature, who knows? speed/ transients is pretty good, but tbh I don’t own any “fast” headphones like Verite, Utopia, or Borealis anymore so it’s hard to say how it stacks up against the big boy cans that are known for speed. Maybe someone from the loaner tour can further explore this aspect. Imaging is good (for a closedback), but not great compared to my modded HD800 and same goes for the staging. This actually has really good stage width for a closedback, but doesn’t have the crazy depth that lets me pinpoint and dissect my music like a good openback headphones. Reasons why you should avoid this headphone: If you absolutely only care about “reference tuning” and anything deviating from that sound is considered garbage, then you should steer clear of this headphone. If you hate bass and think “REAL audiophile music doesn’t have bass™,” then you should stay the fk away from this. If you hate closedbacks, this won’t change your opinion about them, so press the back button NOW If you listen to your music at low db. These headphones kind of encourage you to crank them up so you can get enveloped in the music. I usually listen at around 70-75db, but when I use these, I go up to 80-85db because it reminds me of my carefree years in college going to concerts and festivals with my friends. The great thing about it is that even when I crank them up, the music doesn’t fall apart like HE1000, and it’s not fatiguing at all even after long periods of listening. I’m not sure how healthy this is for your hearing so use caution when listening please! All in all, I’m pretty satisfied with the mods, but only time will tell if it will pass my sporadic gear-cycling tendencies. Therefore I’ll refrain from saying stuff like oh-mer-gawd this is the NEXT BEST THING! However, I think there’s some merit to it when it keeps me up late at night (check my recent status) and helped me take a trip down memory lane to my college years going to concerts and music festivals. I got goosebumps rediscovering old playlists and it was such a pleasant experience despite losing many hours of sleep over it. The slam is so addictive and really made me feel like I was at a live concert. Great job @E_Schaaf and I hope to see more impressions from other friends soon!