My bad then, delete the greenback part. I have a pair of the GT12s in a Marshal 2x12 and love them - high gain goodness but that is what they do well.
Here is a great resource: http://celestion.com...duct/15/g12t75/
Use that and balance your EQ settings - roll back the pre's gain let the master vol do its work - your cab (open - closed, etc) will effect it too. Depending on how ham fisted our bass player is I will adjust mids and highs - bass is nominal as he will carry most of that range. But I do enjoy the early breakup/fizz.
Though if you are having unusual fuzziness (not due to your preamp,etc.) check the hardware and cones - tears happen.
BTW I wasn't being flippant regarding the V30s - sometimes a switch of speakers is the magic bullet we are looking for. Keep your eyes open and if you see a good deal consider trying them out.