Very well conveyed, Les! The only things I have to add are experiential: two situations left me slack-jawed and in awe of what I was hearing, and both involved NOS preamp tubes. Using my MkIII as a test base, the NOS Mullard 12ax7 in V1 made a tremendous impact compared to M/B labeled tubes in the same spot.
Well, you’re the one who convinced me to go to an NOS Mullard 12AX7 in my HXDA instead of just using one of the other NOS preamp tubes I was saving for a rainy day, and it was magic in the amp!
So yeah, it turned into sweetness and it resulted in my buying more for the amp, plus NOS Siemens output tubes.
The DG30 came from the factory with NOS BRIMAR preamp tubes, also of UK manufacture, and what I think are the same EL84Ms as the 80s tubes I bought as spares.
I have all GE preamp tubes in the Lone Star, except the phase inverter that came out of my last Two-Rock, that isn’t labeled, but I’m told is NOS. While it currently has the Chinese made 6L6s that Mesa offers, my plan is to install NOS (either Sylvania 6L6s or Philips 5881s).