I hope you feel you're still getting value out of this thread. Kinda seems to me that what started out as a pretty straightforward quest - to pick up a wonderful tube preamp - has evolved into a somewhat wide open discussion of many wonderful options in which virtually everything is on the table. Except for (maybe) your chosen Salk WOW1 speakers. But I think I read that you are content with those.
Let me share a couple of thoughts on power amps. First, you don't have to stay with the big (and therefore $$$$) names. I'm sure they are nice amps and sound good. But there are wonderful options out there from lesser known builders, especially on the used market. Note that I've not shopped around for any specific amplifiers, but I'm simply trying to broaden your list of possible candidates that should be available without breaking the bank.
Coda would be on my short list. Complete beasts, capable of powering virtually any speaker into harmonious submission and tranquility while provide superb, performance-transparent-insight into whatever recordings you throw at them. Brought to you by the guys who founded Threshold. Sanders Magtech or Innersound Electrostatic. These amps can take an inefficient speaker and make it sit up and play wonderfully. And they are bulletproof.
One of these amps would allow you to comfortably stay with your less-efficient speakers and return to shopping for a killer tube preamp. And this thread is replete with many well regarded candidates. Don Sachs, Supratech, DeHavilland, Atma-sphere, Quicksilver. These would be on my short list, though there are probably other options out there.