I just purchased a Peavey T-Max amp off Guitar Center's website. It features a single tube (a 12AX7 I believe) in the tube pre-amp channel. I want to replace that tube so I know it is new and will have a lot of life (unless it is a dud) ahead of it. I read that pre-amp tubes last a long time. Therefore any suggestions to what brand to look into? This is my first time ever buying a tube.