75-100 watts? Looks like a mean machine; if you look or can find the #s on the odd-ball, pass them along; growing # of tubistas here - plus places to look on the www. Just guessing but the 7591 could be either a voltage regulator or maybe it's the driver. Anyway, thing looks like a powerhouse... is this the one that was sold w/ 2 chasses or I am thinking of the Big Bird?megadan said:Ah, I was wrong again.When I realized the tube in there was NOT a 12AX7, I left the old tube in. I identified it at one point, but now I've totally forgetten! It was all numbers and it was very rare, there weren't any avaliable directly anymore.