Agreed with Nogi to definitely spend more time comparing (sonics and non sonics perspective). From my experience a tough call...almost every single time I've tried the 1Z from late Sept till now I feel the AK380Cu (can't speak much about the std AK380) has a more reference-y sound and the 1Z seems to have a smaller soundstage and a little warmer. At least IMHO there are more pros than cons for the AK380Cu than for the 1Z :-
- more referency than the 1Z
- airier and wider soundstage
- 2.5mm is more common than 4.4mm
- less disparity between the 2.5mm balanced and 3.5mm SE. To me on the 1Z the fact that it shines on 4.4mm and "just getting by" on 3.5mm SE is not a positive point for the 1Z (this isn't just power difference between balanced and SE, but DSD support between balanced and SE too).
- AK380Cu alone is lighter and more compact (although more "edgey" in the hand but not really an issue in the hand)
- faster UI
- std microUSB connector
Despite this, I still bought the 1Z last week and the question remains if I'll keep both or if I'll get rid of one. But the reasons for buying the 1Z
- battery life (this deserves a 2 pointer ++)
- 4.4mm is easier to solder than 2.5mm for DIY cables (not an issue if you don't , but I'm trying to make my own Utopia cables)
- I'm probably bored of referency sound and like something "meatier" and prepared to sacrifice a little soundstage for it
- more oomph in balanced compared to the AK380Cu standalone...naturally AK380Cu with amp will outdo the 1Z, however the AK380Cu+amp is then heavier than the 1Z
So bottom line, I ended up getting the 1Z pretty much mostly (but not solely) for non-sonic reasons but for more practical reasons (esp the battery life and the ease of soldering of 4.4mm). If I end up keeping both DAPs, I think it'll almost be inevitable that that the 1Z will spend more time with the Utopia, and the AK380Cu more time with out-and-about IEMs.