I've got a PRRI with a Celestion Gold in it and play a Tele with a Seymour Duncan humbucker in the next. Have always loved the combination. Sweet and full. The last couple of weeks its been sounding harsher to me and no matter what I do with the amp settings I can't get my sound back. What could cause this kind of change? Tubes? New strings on the guitar? I'm also getting a little bit of squeal from the amp and what sounds like a crackly sound intermittently. I'm grasping at straws here. What do you think?