Hi Lizzy
Anzi... Ciao Lizzy, da un Umbro/Pugliese
Proseguo in inglese per correttezza.
The problem could be in the loudspeakers or in the loudspeakers connections.
Try to disconnect the loudspeakers and power on the unit and set the voulme over 4, does it go in std-by again?
IF YES, there could be a problem in the ampli section.
IF NOT the problem is in the speakers or speakers connections.
If you need help ask here or send me a message
ciao ciao
Eugenio