Volumio s& 3 Issues?
Raspberry 3B with HifiBerry Digi+ on Version 2.632 must select HifiBerry Digi NOT Plus. Toslink Sound Output works with this selection. After upgrade to Version 3, similarly, HiFiBerry Digi must be selected NOT Plus to avoid alsa error. But there is no sound out Toslink
Please see: https://community.volumio.com