I replaced a couple preamp tubes last week (as well as new 6V6's) in my DRRI. It behaved flawlessly at a Canada Day gig - and never went past 3.5 on the volume knob filling the entire room. Took her to practice last night and she just didn't seem to have any balls at all. Quiet - no noise, just sounded like she was weak and for the first time I had her at 5.5 just to keep up with the drummer.
Can that be a bad preamp tube taking gain out of the chain? A bad poweramp tube? Something else?
Any and all insights are welcome.