I'm a real newb at doing anything with my amps. I've always just taken it to a tech. I'm about to change out the tubes of my old Mesa Boogie Subway Rocket. I was told that JJ's are really good, probably better than the Mesa's. Any suggestions on tubes that people really like for this amp...I really don't want to go over $20 or so for each tube? Also, you just have to take off the back bar, and then unclip the metal around the 12AX7's correct? Other than that it is just swapping them out, no biasing or anything like that?