supysonic-daemon is an optional non-exiting process made to be ran in the background to manage background scans, library changes detection and the jukebox mode (audio played on the server hardware).
If supysonic-daemon is running when you start a manual scan using supysonic-cli, the scan will be run by the daemon process in the background instead of running in the foreground. This daemon also enables the web UI scan feature.
With proper configuration, supysonic-daemon also allows authorized users to play audio on the machine’s hardware, using their client as a remote control.
Bugs can be reported to your distribution’s bug tracker or upstream at https://github.com/spl0k/supysonic/issues.