Alright, I couldn’t find such an app, but I managed to write a rudimentary app myself.
I can select an audio file in the app, connect it via USB-OTG, and press a footswitch on the QC to play the song. This is very cool!
If anyone is interested, I can release the source code and we can further work on the “QuadCortex Audio Playback app for Android”.
I’m using the default MediaPlayer in Android, and I seem to face the same problem as reported here.
There’s a disturbing bit-rate drop (for the lack of actually knowing what is happening) for about 20 seconds, and then audio playback returns to normal for another 20 seconds. This alternates for the remainder of the playback.
If it helps, I can record the headphones output so you can have a listen to the problem yourself.