I have a KA-8100 that is in pristine visual condition. I have it tweaked (+1.5 db bass) to sound pretty good thru a pair of Sennheiser HD 800's. I want to rehab it so that it will last for a long time (10 years anyway). To date I have replaced all of the caps and zeners on the Control Amp board and am wondering if there is anything else to do to that board to a) make it sound better. b) make it last longer. c) improve on the original circuity? I have also replaced the main filter caps on the Power Amp board. Same question: Anything I can/should do to that board to improve performance/longevity? I'll probably replace the caps on the Pre Amp board and have the same questions for that board. I know that I am asking a lot of questions but hopefully someone might want to wade in with some answers?