I have the above amp... its about 9 years old. The problem: Presence control on both channels- They use seperate pots for each channel. This knob suddenly does NOTHING until you hit about 9/10 then you get 100 percent presence, anything below 8.5-9 you get ZERO presence. This acts the same on both channels! Is your 6505 112 the same way? I feel like I used to run the presence on about 6 or 7... now its always pretty much 9! I tried replacing: C28, R111, R10, C56, R85. These did NOTHING. -Can't be the pot since both channels have their own, and the problem is common to both. Am I totally insane? Or is this how all the peavey 6505 112s are? If you guys could tell me if you have the same problem or if mine is bad that would be great. PS: tried the FX loop thing... presence acts the same with or without that buffer active.