The volume on my Hifiberry DAC2 pro headphone output cannot be adjusted. Neither via the Alsamixer nor via settings in the piCoreplayer can the volume be adjusted.
I tried the Hifiberry OS, which does not even manage to integrate my NAS as a source. But here, too, there is no way to adjust the volume as needed.
Another problem is the incorrect assignment of the DAC2 pro in the Squeezelite settings of the picoreplayer. This can be solved, but it is unattractive.