We hacked this vintage GE tube radio to be a guitar amp! 1/4" input jack on the back.
The volume knob is the one furthest to the left. The next knob is "AFC" is a click knob and seems to add some mids and resonance. The other two knobs are for aesthetics only.
This model doesn't get very loud, making it perfect for a bedroom practice amp or recording amp. There are two speakers inside.