Have been lurking and not posting much lately, but I just spent three days with a friend's 200hrs+ ran-in zx2 and isn't seeing the hype from the folks on the zx2 thread. Tempted to post my impressions on the thread but why derail the hype train!
Seriously, zx2 does sound nice and I think a huge step up from zx1 (wasn't a big fan of the zx1 sound). Gone are the somewhat brittle and lean zx1 sound that often felt artificial to me, and despite the low rates power it does drive my c/iems adequately (could always use more power).
However, in the pure SQ pecking order, I would rate zx2 along with ak100ii and clearly below Hugo/hm901/paw gold/ak240. I would put the zx2 below the ak120ii/calyx M too. Didn't had a Flow or ARM2, and never spent enough time with P1 to comment on these. My biggest gripe against the zx2's sound (with all "enhancements" turned off) is that it still isn't as transparent as I would like, and lacks the note weight/attack to reproduce proper instruments timber. I find it pairs better with thicker sounding IEM like tg334/1964ears v8 than a more transparent one like an UERM/1plus2.
The strength of the zx2 is really the android /w playstore support, as well as battery life when used standalone. I had been forever looking for a "serious" Spotify dap (ideally with 4G support on top of wifi). Zx1 for me really excited but fell way short in sq. Zx2 improved the sound, but still some ways before it can displace my better DAPs and is way bigger/heavier than zx1. And most importantly, the deal breaker might as well be due to another sony dap - A17, which sounded very nice and have a similar signature to zx2, not unlike how F887 made it difficult to pay a premium for the zx1. I just hope Sony will put this S-master HX on their Z series phone.
Really wanted to like the zx2 but guess I will pass and see what Sony do next.