Newbie here.
I've got a Hifiberry Digi+ and Pi3, with an attached external USB harddrive having its own power.
I'm happy to report that it seems to be working great for playing tunes from my USB drive and streaming audio from my Linux PC.
I do notice that adding mp3s (with the same ownership as I notice on the other files, "mpd:1000"), to the drive and clicking "rebuild library" seems to have no effect. The workaround to get an updated library is to unmount the drive, rebuild the library (i.e., clear it), then remount the drive and rebuild again.
I'm looking for ways to contribute on a very limited basis; this is just one of many little hobbies.
One feature that I thought might be useful is if someone could provide instructions to verbose log to an external drive. Then the system could be left on with full debug logs indefinately, assuming performance is still good, and then in the rare case that the system crashes there will be some debug info. Things seem pretty stable, by the way.
I also thought it would be nice to try and get the system running (perhaps with reduced functionality) with the SD card mounted read-only, so that fsck wouldn't be so much needed in the event of power failure. I'd be interested in working on that so let me know if anything comes to mind w.r.t. pointers on where to start.
So far I haven't noticed any clicks when changing tracks. I'm using the optical digital output, with software volume disabled. I haven't tried choosing tracks with different bitrates or anything though.
Streaming to the box via UPnP and DLNA works great. I used pulseaudio-dlna (
https://github.com/masmu/pulseaudio-dlna).