Hi, Xperia M4 Aqua (E2353, 5.0, 26.1.A.2.167, unlocked bootloader, TWRP, rooted) works once the relevant lines for high-res audio or 24_bit audio are added to build.conf and audio_policy.conf.
The build.conf was edited based on a copy that someone pasted in one of these threads. (just the compress-offload line, as well as the deep-buffer one for the heck of it)
The audio_policy.conf was edited based on these files that are supposed to work with CM12.1 and 13 and not original ROMs. I carefully added just enough samplerates, formats and devices that refer to high-res audio in any way, did a restart, and Poweramp began to sing. Didn't seem to need the mixer_paths.xml .
http://forum.xda-developers.com/m4-aqua/themes-apps/cm12-1-13-192khz-24b-hi-res-audio-m4-t3377706/
There is no lag when using the Sony API, but clipping may occur unless clipping protection is used in Replaygain. There is volume change, track change and seeking latency when using the default Snapdragon, but no clipping ever occurs.
1st image - no resampling, "OEM Variant" option checked
2nd image - no resampling, option unchecked
3rd image - resampling to show highest samplerate support 96000, option checked