Yeah baby....I found a mate

Jsujo, good deal! I was about to write the same - sell the DMT-12 & get the DMT-15. seems like you had the same idea well before me!!
That's what I found - if you want a speaker for a medium size rm go for the DMT-10. If you want one for a much bigger room, skip the -12 & buy the -15 directly.
Will cost you! but it's worth the wait & money. Good luck!

Creeper.. i forgot to answer you tube question.

I have Telefunke 12AT7'a (not the $$$$$$ kind), the 6SN7's are Tung Sol or Raytheons, the 6JN6's are RCA's.

The Raytheons do one hell of a job!

Ironic, as I just purchased a pair of Raytheon 6SN7-GTB to try in the input stage of my monos.

Silver twins that sound as lovely as they look, perfect.

If memory serves, the Tannoys are bi-wireable. You should consider experimenting with horizontal and vertical bi-amping as well. Lots of options having the pair now.

having some trouble with the second amp I just got...This amp was modified by adding a volume knob, with a tube driven line preamp inside,,,very weird...and I am getting a hum which I suspect is related to that addition.

My first guess would be that a tube was jossled and damaged in transit. Try swapping the tubes from the good one into the new one and see if the hum goes away. If not, contact David again. Chances are he did the preamp mod himself. He'll know what's going on.

Good luck and keep us informed. When you get it figured out, I'm sure you'll be happy with the purchase. I've always been impressed by David's designs.