It took me quite some efforts since I took over the old "MP3 player" but now the second feature release of Audio Player is available in the App Store, and on GitHub.
At the moment I am waiting an app review to get away from the "experimental" status.
v1.2.0 (2016-09-09)
* fix: wrong spinning wheel location in css
* fix: cover art crop box more flexible
* fix: album transparency
* enhancement: rework of sidebar with integrated playlists in dynamic navigation
* enhancement: performance improvement when loading categories
* app:code-check compatibility
* app will be signed as of this release
full release history
Any feedback is welcome! 