Hello all: Been a member for a while, but only spectating; never owning a real all-tube Marshall. Had several AVT-50's (tube preamp), but just purchased a 10/20w DSL 20 head last year. Two unusual characteristics: when using the foot switch, no audible noise from "gain" to "ultra gain", however, when going back to gain there is an audible pause and then click. In addition, my clean EQ settings shift to mid/dark/muddy on ultra gain. Any suggestions such as a checkup at a reputable amp shop? I find it hard to believe my pre-amp tubes have gone bad so soon. Also, I run a Keely comp/sustainer along with my other time-based effects through the amps effects loop. Could this be the problem or perhaps yank everything out of the effects loop and run it between guitar and amp front end with a Spark line boost? I know I may get negative feedback, but my Peavey 40w ValveKing was my best amp ever but 3 back surgeries put an end to a 50lb haul. Thanks all. If I could get EQ consistent across both channels, I'd be happy. I play everything from Airplane to Deep Purple, Pink Floyd to Queensryche, so I need flexibility and a channel switch pedal that worked would be a good start!