USB Soundcard restarts when sound stops

suggest disable pulseaudio module suspend-on-idle temporarily

pacmd unload-module module-suspend-on-idle

if that works Pulseaudio configuration can be changed to disable the module permanently

sudo sed -i 's/load-module module-suspend-on-idle/#load-module module-suspend-on-idle/g' /etc/pulse/default.pa

this adds a comment tag ‘#’ at the start of the line to stop module being loaded