ok, it's already much better... I have one last question, following this guide:
LibreELEC installation and configuration | HiFiBerry
when I give the last command I get this message:
LibreELEC (official): 11.0.3 (RPi4.arm)
LibreELEC:~ # amixer -c 0 set Digital 80% amixer: Unable to find simple control 'Digital', 0
Suggestions?