No sound comes out

Check the speaker connections and connections to the other devices. link

Alter the input selector to match the input connector (BALANCED or UNBALANCED) of the connected device. link

Insert connection cables all the way in.

Check that input connectors and output connectors are not reversely connected.

Check cables for damage.

Check that speaker cables are properly connected. Check that cable core wires come in contact with the metal part on speaker terminals. link

Securely tighten the speaker terminals. Check speaker terminals for looseness. link