I really liked TAD 6L6 WGC-STR with my 5150II. Then a Tung Sol 12ax7 in V1. Then you can easily get away with cheap Chinese tubes the rest of the way. Or add a Penta 12ax7 for the 2nd gain stage to "tame" it a little bit and warm it up. I really liked that cuz it got ride of the "sizzle" or fizz associated with those amps.