Hey I am hoping maybe someone else has had this issue and knows whats up. One of my 12au7 driver tubes went recently in my SVT II pro, and I replaced it. I had trouble biasing the amp properly as the side that was replaced seemed to be overbiased no matter what I did. I looked up in the manual and it claims that it means the tubes are not matched... makes sense. I replaced both the driver tubes with a matched set of 12au7's and I still get the same conditions. I am hoping this does not mean the power tunes are going on the one side but I fear that is the case. Any other causes to this? I have done some studying and come to the conclusion it is ok to run the amp like this but that I really should find the cause and correct it ASAP. I am an engineer and have alot of experience repairing and maintaining equipment, not tubes, but I understand all of the safety precautions and theory behind them, so I will be doing all the servicing myself. Could it have to do with the actual circuit perhaps? any help or hints would be appreciated. PS: As an addition, the tube was not overbiasing before it went on me, I am kind of a nut and regularily check my biases.