The phone is a HTC Sensation, I'll try and find out what the actual audio spec is. They did release a Beats version (Sensation XE) which was actually exactly the same spec, just CPU clocked a bit higher and came with some Beats earphones so I imagine the audio side of things is reasonable.
I bet the Galaxy Ace is more than good enough. First of all I'd copy some music to it and just try it.
Edit: If you want to use the Galaxy Ace as the music player but to also control then you'll need a music app rather than use aMPD.
EDITED: 13 Jul 2015 09:27 by ANT_THOMAS