Besides the speaker configuration, gain modifications, and the middle control on the Super, what exactly is the difference in design... in layman's terms? I've had my eye on a Vibroverb Custom but yesterday a guy in town put up an original 64' Super with period correct Concert transformers and a JBL-D-130 in it. He wants $1700 for it. Do the modifications decrease its value; is $1700 being greedy? ...The middle knob on the Super seems like an understated selling point... thoughts? ~As per the poll; I'm talking about an all original 64' Super as opposed to the modified one above. If you can, exclude the collectible nature of these amps and focus on performance.