After a mild trashing of my SD30II, I invested in a total re tube after one of the preamp tubes failed. Ruby 12AX7ACZ HG+ #1, jjEC83 S #2 and #3 and a quartet of jj EL84's. Wow! The amp sounds 10 times better than it did new. The 5u4 rectifier is orig. My amp just sings and finally I have found the true potential of this amp. I am floored beyond belief. Tons more volume and airiness as well as some gorgeous chime and jangle. All that through a single V-30 cab and mim strat with area pups. I am a HAPPY man again!!!!