I have found that the drive/power tubes do have a nice infuence on the sound. The 6de7's have more attack and synergize better with the detailed Bendix tubes in my DAC. The 6ew7's have more decay and a wider, deeper soundstage, and they seem to compliment the WE396A in the Paradisea which exhibits these same traits. In both cases, this is with the Sophia rectifier. (I don't see any reason to roll something else into the rectifier socket - it's that good!)
This is almost like having two different systems to synergize with headphone choices or music genres. I find I prefer the 6ew7 sound and I would choose it if I was forced to pick one combination for all situations. Fortunately, I am not restricted and I can roll these various tubes for the variety.
I suspect that one could find rectifiers to support these two different signatures if a Sophia 274B was out of the price range. I know that the 5R4GYB works very well with the 6ew7's for a wide soundstage and smooth sound. I think that the 5U4G or 5AR4 might be the best match for the 6de7's, but I haven't gotten to experimenting with those yet.