Don't know if this volume boost old trick works on the EUR model, JP / Asia model can do this if you wanna feed some power hungry babies with ZX2, but you will not able to do any EQ/ sound effects with this app turned off.
http://www.head-fi.org/t/742609/sony-nw-zx2-hi-end-dap/1890#post_11358720
I think ZX2 still best matched with Z5. Z7 better goes with PHA3 in balanced mode
Pha 3 is an excellent portable Amp with more than enough capability to do a lot of high-end audio stuff. But I can not stretch that enough, the PHA 3 is built with internal DAC which some people prefer calling them Analog amp. The ZX2 is utilizing simple but rely heavily on design, shielding, circuitry components....etc and Sony design it own Class D amp. They call it the S-Master HX (people call them direct digital ? Or simply class D). So the things here is that
1/ ZX2 Aux out and connect to PHA-3 as analog connection, the Amping will come from PHA3, and the PHA-3 circuitry and design will more or less effecting the original analog from ZX2. More than a few people reporting that the Z7 will has thinner sound this way. Some even report better and wider soundstage with balanced connection, which is true as balanced will always have that effect. The ZX2 do also has balanced out, but I doubt any others had tested it yet.....in a sense, to compare between balanced and vs regular output.....the differences will always present, and it always is not the proof that the Z7 was badly driven by ZX2 or better driven by PHA3
2/ ZX2 digital out to PHA3 will be all 110001001 (digital) and only act as a transportation, in which case even a smartphone can do the same. Some may argue that smartphone as a transport will have more noise and distortion, but in reality, the PHA-3 is more than capable at clocking, filters them out and make it sounds wonderful just as ZX2 as a transport.
While I have not personally experience the PHA-3 and Z7 to compare, I still am very interested at how different they sound. If anybody can share the experiences in details, it would be wonderful.
The one thing I am so sure that Z7 can fully be driven by ZX2 alone just based on 2 facts.
1/ I amped it with Yamaha RXV477 via Aux....and it just sound thinner in tonality, but similarly as loud. That was to call it a simple comparison. If it was much better amped rather than straight outta ZX2, I would have returned it for sure.
2/ Z7 shows much, if not better details retrieval, soundstage, instruments housing than my IM-04 with upgraded cables.
All in all, to use ZX2 balanced output, I am awaiting my cables