a little more infor....... I think it might be something to do with the pre-amp section. When I plug my PODxt into the effects loop and my guitar into my pod, completely bypassing the pre-amp, there is no buzz/humm. Could one of the pre-amp tubes be bad or going bad? If so, I'm thinking about changing out the tubes anyway, and wander if anybody has any experience with electro-harmonix tubes. I'm thinking about going with the EL34's (since there's a bias switch for these inside the head) and some new 12AX7's. How much would that change the sound as apposed to the stock sovtec(I think that's what peavey uses) 6L6's and 12AX7's?