Having beaten Italy 3-0 on Saturday, Spain led 3-0 inside 16 minutes in Vaduz through goals from Sergio Ramos, Chelsea's Morata and Isco.
Manchester City midfielder Silva added a fourth before Iago Aspas made it 5-0.
Iago set up Morata's second then scored another of his own before Max Goppel's late own goal completed the rout