I have this Rivera R-55. Its 9 years old. When I play in the hi-gain channel, there is this bad ugly distorted sound that it emits and it gets worse with more gain. It only does this when I pick and is much worse on the higher notes, especially high up on the neck. If I do hammer ons or pull-offs, it sounds great its just there during picking attack. It sounds like something is clipping and I hope someone can help me with this. My suspicion is this is a cap or something that needs replacing. I currently have 2 other amps (1987 Marshall clone and Budda SD18) and neither of these have this problem. Heres what Ive done so far: - Tried several different picks and looked hard at my technique its not me or my picks -I plug straight into the amp with a 10 Fulltone cord. These are excellent cords. Nothing in the loop just straight guitar-amp. -Tried several different guitars HB PUs are much worse and the hotter the PU, the worse this is. Both of my Les Pauls do the same thing. -Tried lots of new tubes .pre-amp and power as well as checking the bias. New tubes help, but its not tubes. -Made sure all tube sockets were clean -Tried this with 3 different speakers with good cords. Ohmage was correct. Guitar techs in my area are not aplenty. It would be helpful if I had an idea what was causing this cause this is really a nice amp that I like a lot. Thanks!