Having the ZX2 for quite sometime now, and comparing to the 1A, 1Z, ZX300 and some other DAPs I've tried before (SP2000, LP6K, SR15, Kann Cube, etc.)...
I truly think the ZX2 can hold its own despite being five years old. The sound is highly detailed, captivating and pretty addicting. It gives notes an excellent weight to them and matches very well w/ more neutral leaning IEMs (ex: in my instance, the Viento-B and Andromeda MW10). Listening to it w/ those IEMs makes me feel like everything is so real...a stage kind of feeling vs. my 1A is more neutral orientated and gives a more technical/uncoloured level of presentation. I think my favourite parts of it as the bass and vocals. The vocals just sound so spot on with excellent weight and timbre. The bass extends very deep and is very controlled. Imaging is also super fantastic, with tons and tons of black space between notes and frequencies. It gives a "floating" type of presentation which I really enjoy, makes me feel really part of the music.
Other positives about it are the excellent battery life. I disabled all apps and processes aside from the music players as I don't need streaming and the battery lasts pretty long. I also quite like the weight of the player, makes you feel like you're holding something substantial. The UI is surprisingly fast too, and the screen size sufficient without too much extra fuss.
A downside I suppose, is the pairing can be a bit intense w/ more bass heavy IEM. With my Trio, I feel like the bass is a bit too strong for my liking, despite still sounding great. With my Trio, I prefer the 1A's neutrality a bit to hold it back.
Overall, an excellent source and companion. Highly recommend.