I spotted an Edition XS on Amazon Warehouse for 340€/$ and the condition was the lowest (acceptable) so I thought to give them a try since I can always return them as well. Turns out the condition was mint without a single speck of dust on them, but they were missing the cable. So either someone returned a pair that has been lacking it or snatched the cable and returned what I believe to be a completely unused headphone. Yay, as they say.

I've been spending a few days with these and just did a more formal playlist testing and I have to say these are seriously good even without EQ. The tonality is not quite the best I've ever heard, but very very close. These sound great with almost any music as is. Just a little lack of bass and some not-so-bad sibilance (Melody Gardot) were the only issues I was able to spot in my test with 10 songs from Chris Jones to Opeth. I'm used to hating the sound without EQ almost on every headphone so it is a very pleasant surprise to be quite happy as is. All the technicals are 9/10 or above with a nice open soundstage that doesn't ruing intimacy or make music feel distant and allows for a great sense of space when it should (London Grammar, Plini). Separation that makes the messiest of metal passages very readable (Opeth). Macro dynamics (speed) that have nice energy and drive and tactility in the bass (Daft Punk, Dream Theater). Timbre and detail that is very natural and pleasant (Chris Jones, Adam Baldych). Everything is just great. I still can't believe these do Opeth well even without EQ.

Comfort is fine though a bit bulky and even if there isn’t particular clamp they put some pressure on the jaws that builds over time. For me at least. Comfort is more individual than sound preferences.vs

LCD-X (2021): I compared these to a few headphones and felt that the twice as expensive LCD-X is the closest competition. Arya (pre-stealth at least) had much worse bass even with EQ and timbral issues so I'd much prefer these. Ananda is really nice, but I can't think of a reason to pay much more for them and they also need EQ more. LCD-X and these go head-to-head in most ways when EQ'd, but without the Edition XS is an instant winner 100%. When EQ'd to Harman these have a bigger soundstage, but equally distant from my ideal staging so I'd call it a draw. Separation is a bit different with these since the larger soundstage places instruments etc further apart, but the LCD-X has better clarity within the stage in a way. Hard to compare. Timbre is a bit better on the LCD-X in the bass and mids with some strings and drums having more saturation and texture, less airiness, but the highs are cleaner on the XS. LCD-X has a bit more fuller sound and the bass is heavier and deeper so for EDM etc I’d take the Audeze for sure. Overall, I’d say that if you want bigger soundstage and spend half the money then XS is the obvious choice and you’re certainly not missing much, but if build quality and the mentioned benefits sound attractive then LCD-X is a solid choice though harder to EQ well due to higher unit variation. I’m not yet sure which I would take over the other, but I could still sell my LCD-X that’s in warranty and make about $500.

vs Bathys: I haven’t spent enough to time with the Bathys to be absolutely certain, but I’d likely take the Edition XS over them. Bathys are a fantastic Bluetooth headphone with a great tuning, but it is a closed back and didn’t seem to particularly excel in anything while being good for the price.

vs HE6se: Here we see that the XS is nowhere near the technical ability of the HE6se V2 except in soundstage which is rather small on the latter. The tuning is a bit better on the HE6 and everything from bass impact and detail to timbre is just a step (or three) above.

Conclusion: Hifiman has put out another top tier contender for a price that is extremely competitive when it comes to sound performance. What Sundara is at the $300 price range these are for the $500-600. Just excellent and certainly very difficult to move up from. I’d take an LCD-5, Susvara, HE6se V2, maybe HE1000se V2 and potentially LCD-X over the XS, but I struggle coming up with much else. Nothing Meze, Focal, Sennheiser (HE-1 not included) or Beyerdynamic. Haven’t heard DCA or ZMF’s so maybe there’s something. Really makes me think that Hifiman is in a league of its own in sound price-performance nowadays.

Edit:

Gaming: these don't do well in directional clarity just like every Hifiman I've ever tried. They're of course fine and better than most gaming headphones, but nowhere near K 240 etc.