Hey Guys, I have an older Mesa 50w Rectoverb (Single Rect, black shadow speaker). I think its from 2000. For the life of me I can not get a good heavy/crunch sound even with the amp cranked a bit. Tried many, many knob configs... I've tried with my rga 121 w/ dimarzio titans as well as my rg570. I originally bought it with JJ EL-34s and have now put in the Mesa 6l6 branded tubes. Do the preamp tubes generally go bad after while?? Could they cause a lack of nice sounding gain? The amp doesn't really buzz to much and the cleans sound amazing. Anyone have any advice?