I've recently bought a used Hughes & Kettner Studio 84 (same as the older Tube 20) amp, see picture below: The amp has variable wattage (0-20 watts) and has two footswitchable channels. I really like the features and think it would be a great amp if I can just get a few things right. The clean channel sounds good, but the dirty channel sounds like the amp has a blanket over it. I've been using my p-90 equipped guitar and it still is very dark. I tried my Les Paul yesterday and it was pretty much un-usable. I've tried swapping both preamp and power amp tubes, as well as upgrading the speaker to a Hellatone 30 (G12H30). While all these helped the overall sound, I can't understand why the clean channel sounds clear and not muddy, while the dirty channel sounds like a blanket has been thrown on my amp. I have heard that H&K amps are normally bright and articulate, but the dirty channel definately isn't. I've also had EQ and OD pedals suggested to me but I'm beginning to suspect that something minor might actually be wrong with the amp that is causing this. Can anyone suggest what it could be, or direct me somewhere that I could get some more information?