So Doug; you post a good summary of the amp with personal observations and clues to how it could be done... Then you wipe the slate and offer the concept that there is; in the 813, a real tube to deal with that promises so much more. I for one am in for the long haul; so whats it gonna be? Why not just do it once for the gipper? You have tried them all so there's a leg up on all of us. Or does it really matter that much which triode you use? Thanks J.R.