Well, I own a Rocktron Vendetta combo and I've had it for a few years. Problem is: I fired it up yesterday, and it barely had any volume. So my first thought is that a tube is dead. So I swap out each preamp tube........in certain combinations I had absolutely no sound. So I kept swapping....found a combination with the bad tube supposedly out. Now the amp only plays half volume, not half power. It's simply just not as loud as it was earlier this week. What could it be? Here's the cronological order to what happened: Last week: Swapped out EL34s for 6CA7s......(biased with test points). Also changed out most of the preamp tubes.....added Tung sols. This week: Played it all week fine and actually was sounding REALLY good. Shut it down two days ago in working order. Yesterday: Turned it on to jam......noticed the volume difference right away. Swapped preamp tubes. Since that didn't work, I put the old EL34s in it and re-biased. Still half volume. It sounds fine, just quiet.....the global density and presence don't seem to do as much either. I can crank the master volume to get it loud, but normally anything past half way would blow my windows out. Can anyone help? I'm trying out for a band next wednesday.