I need to replace my preamp tubes due to that annoying microphonic noise. Its been at least six years since they were changed out. Would it be ok to use the Elecrto Harmonix 12ax7's in all 5 positions? I found a good price and I'm on a budget right now so this is one of my only options at the moment. Thanks for any help guys. Its my first time replacing them in this amp and I want to do it right but not spend too much.