I have a Peavey TB Raxx bass preamp. I am the original owner. It seems to be working fine, it does not give me any problems and I have it paired up with a Crown XLS 1000 Drivecore amp. It has the original tubes. And like I said, it seems to be working fine. It uses 2 12ax7 preamp tubes. Would I notice any difference if I were to install new tubes? What would someone suggest? Groove Tubes, EHX, Mullard, Tung Sol, JJ, Ruby?