look around at the back/front of the amp usually if it's a tube u will see a glowing tube inside, or if not check if it has a standby switch, simple enough
Mai 5w Crate Tube Amp doesn't require a standby switch.
Neither is the tube exposed to anything.
Weird huh? The whole metal plate controls just heats up like crazy
And yes, the manual says it's a 5w tube amp. Haha.