Test build for #159, not a release. It's 1.6.0 so far plus one change: a USB DAC gets the same 500 ms audio buffer as the headphone jack. Stock firmware gives USB only 100 ms, so a hiccup at a track change longer than that is heard as a gap.
Install: copy update.tar to the root of the card, then System settings → System Update → TF card update. About shows 1.6.0 Pod dev 447. Network Update takes you to the next release when it's out.