Which Bassman Is This? I have a chance to get this for really cheap, but I'm not really sure what it is. The rear shot makes it look like a single 15 because the floor tiles measure out to less than 24" but my main concern is the horsepower. I cant see what it says underneath "BASSMAN". I understand there were some 55 Watt, an 85 a 100(+) Watt. Can we count tubes or knobs and figure out what this actually is?