Hi all, I'm not a great reader of schematics so I wondered if anyone on here would be able to help with these questions? 1. The valvestate 8100 doesn't have a presence control. Is there anything in the schematic that indicates that in the power amp stage there is any presence added or anything that would make the amp brighter when the signal goes through that stage? 2. I've always thought that the bi chorus 8200 was just the chorus version of the 8100. I have both heads and they do sound different to each other (both great). Not completely different but definitely different. Am I just hearing a slight difference that would be normal say if you had two amps of exactly the same type next to each other (but maybe one was a bit older or one had been serviced recently with some pots replaced) or are they fundamentally different heads from the start?