Audio only stutter

[Skywatch]

I hope you don't mind me jumping back in here, but could you copy some music files from the HDD to the SD card and try playing them from the sd card? That would help see if the issue is in the usb route to storage. Just a thought.

Also, do you have a spare sd card that you could put a fresh image on to see if maybe there is corruption on the current card that only affects music only playback?

I have a probable corruption issue with one pi2 now where databases no longer load. Everything else works fine except sometimes audio goes out of sync with video. A reboot and it's back in sunc again.
I'm going to rebuild that system from scratch soon.