Ok, I've got a Peavey 6505 2x12 Combo with 2 stock Ruby 6L6GC power tubes, and to be blunt, they suck, way too tinny and frail. I play with EMG 81 and 85 pickups; could that be the case? I was thinking of switching the tubes out with EL36s or something along the lines of that low end, fat sound. Any suggestions on how to get a better, thicker sound?