My amp is technically a SPUD I guess, EL34s and OPTs are all there is. There's no voltage gain though, it's actually slightly negative gain, but many active preamps are capable of driving it. I use one of Broski's Aikido designs for voltage gain, 6SL7s then a 6SN7 buffer.
I've also considered installing a switch to change from OPT output to an interstage with the EL34 driving yet another amp stage, 211 or GM70. Although my speaker really only needs more than EL34 level power if you want very high SPLs. It drives a 4.5" wideband with a light paper cone in a 330 Hz JMLC + a Fostex T500.
Speaking of 6SN7, these can be used as PSET. There was one at RMAF a few years ago, though I forget exactly who made it. It was a small company with a pair of massive high-eff speakers driven by the 6SN7 PSET. I might rather go with 12BH7 but not sure I'll ever try this!