V 2.029 - Cubox-i2eX with USB-DAC
Just in case, someone else is having this problem:
After installing the Spotify plugin there was no sound from the plugin.
For some reason, setting Output Device to USB-DAC again, fixes the problem.
Also - Spotify plugin currently only seems to be working with hardware mixer, so no volume control yet for USB-DACs. Maybe this is related to the above?