I have only come to the idea of using my phone for music because, having bought a Z3 for general phone functionality, my iBasso DX50 decided to stop working (headphone jack came apart inside,for the second time). What to do? While researching the options for repair or replacement, it seemed obvious to slip an SD card into the Z3 and plug in the Shure S535 phones.
Despite Sony's advertising claims about HD sound (and the capacity to play lossless files, which had been a marginal selling point), at first I was surprised that that, being a phone, the sound was anything other than pathetic. Using either the Walkman app (more below) or a free music player that appears to use the native Sony software modules (same equaliser, menu of surround sound effects etc), the sound was reasonably musical. Compared with dedicated music players of even a few years ago, really not bad. But after a few hours. the deficiencies became clear. Though warm, the sound was pretty mushy, the entire sound stage being heard through a thin layer of soup, and completely lacking in layering, or precise location of instruments. This was with all "effects" and equalisation switched off. I experimented with the surround options, to see if this induced a better spatial illusion, but all I got from it was a added reverb and a few db of extra loudness.
So, while researching my next DAP purchase, I came to this thread. A lot of the assumptions behind the debate were not really ones I shared (including the premise that even a top-class phone can be a satisfactory music player). It certainly doesn't strike me as sane to buy a £400 phone and then root it, in the near certain knowledge that some functionality will be lost and the warranty invalidated. On the other hand, I could see that there was more genuine audio technology in the Z3 than I had realised, and serious people were prepared to compare it to at least a Fiio X1. Despite this, the sound was like soup.
A breakthrough came, thanks to a sane voice on this thread, which referred to the possibility of downloading different player apps, specifically Neutron. This removed the soup, banished the unwanted warmth of the Walkman app, and created a layered soundstage with pinpoint location (specifically the winds and the different string sections in a Mozart piano concerto). The phrasing of the individual parts came to life, and the logic of the performance emerged. An hour or two of A v B listening established that this was not some sort of placebo effect. On the other hand, thought decent, the sound was pretty lean. It could be criticised for being a bit more digital, less musical, than is ideal. It is not as good as I had been getting from my DX50. But at least the music can be heard, and enjoyed. And, as mentioned earlier in the thread, Neutron does contain an independent virtual volume slider that has more stops on it than the rather coarse physical volume control on the Z3. It is surprising that a media technology company like Sony should, apparently, have so little understanding of what the end-user wants from the product; their software approach entirely masks the potentialities of the hardware.
Where does this leave me? The Z3+Neutron combination is good enough to save me from buying an entry-level DAP as a stop-gap. On days when only one device can be carried around, this is going to be quite satisfactory. For under £5 additional outlay, that is pretty good. The combination is not good enough, on the evidence of my ears, to be the solution. So I shall continue to search for a dedicated DAP that makes a more complete job of realising the musicality, as well as the analytical structure, of the music that is on my files.