We have Android 5 (Lollipop) tested using the Sony Xperia Z2 Tablet, the results are as follows:
1) Sony Walkman – there are no longer settings for external DACs, the DAC (tested using iDSD nano with latest beta code). All audio is up-sampled to quad speed (176.4/192kHz), so never Bit-Perfect. Android Volume control sets DAC Volume.
2) Spotify – plays audio also as Quad Speed upsampled (this may be Sony specific). Android Volume control sets DAC Volume.
3) USB Audio Player Pro (UAPP), took two restarts before it could grab the DAC, after that works normally, bitperfect the Android Volume control does not change levels.
So UAPP remains recommended for HD/HiRez and high quality playback.
For other audio player apps etc. the Android volume control should be set to maximum to avoid “loosing bits”.
We hope you found this useful.