Anybody ever seen one of these before? It measures 7 in. by 6-1/2 in. by 3-1/2 in. It looks like an old 5 channel PA amp, but it's so tiny... why 5 channels? The speaker is a 3 in. speaker. The middle knob appears to be a volume-on/off. The left knob has 5 positions and the right knob appears to have a spring thingy inside. It moves and goes right back... a mute maybe? I think this will be a very cool guitar amp to record with. There are no markings so I have no idea what this is... do you?