Greetings, Forgive me if this has beed answered . Plain and simple, I want to replace all tubes in my amp. I have had this amp since 1984 and re-tubed it w/ many different brands over the yrs. The tubes in it are very old.I know good pre's can last a long time but I feel as tho they need replaced. I have been struggling w/ it for weeks trying to figure out what happened to my tone. I want dimension in my tone. I have tried Sovtek's, Svetlana's, GT's and Mesa tubes. I know that the V1 pre socket is the most important but when I view the schematics, they all seem important. I still think to myself do tubes change tones? Or do they just make the amp function? Like PU's, Speakers...ect. They can change tone. Jeesh, anyway, any guidance will be greatly appreciated. I love this forum. Very informative. Thanks for your time, James