Interesting post. Good stuff being discussed, but if your analysis of the the '302' is the same as mine, that is if anything the highs are a bit rolled but the mid-range and upper-mid range are a tad too crist (too fast or shortened decay, perhaps) then a SOTA pre-amp may be less of a solution than a pre-amp that allows you to get where you want to go by tube selection. FWIW, I never got where I wanted to go with my '302' direct to 6 different amps with all kinds of tubes, nor thru a couple of excellent pre-amps with limited tube selection. So far it sounds best to me using some fairly modest stuff (amp and pre-amp) which is very tunable without breaking the bank.
FWIW.
FWIW.