Tube amps under $7500

+1 @larryi 

My listening values are pretty much the same.  I have no experience of Legacy speakers but I take the OP at his word that they are non-negotiable.  That’s why I suggested the possibility of bi-amping, as one approach to solving these simultaneous equations.  But for me, with my listening values, if I wanted to experience the magic of tubes, I’d think about easier-to-drive speakers.  Having said that, the OP is taking a nicely deliberate approach and might just be able to get it all with the Legacies and the right tube amp.  And I’m enjoying trying to help. 

The MC275 is a great amp once you throw away the junk OEM tubes. Which should he done with immediacy IMHO.

@mdalton 

Bi-Amping is the way, at least for me.

I have two mono-blocked MC275s (running GEC A2900s and KR Audio KT88s or GEC KT88s depending on any  given day) up top and a pair of Pass Labs xa160.8 mono-blocks down under. I love how they sound together.

Speakers are BW 802D4s.

@larryi I'm told that many tube users are switching to Coda SS amps. Extended bottom end is a necessity for me.
@mdalton Sounds optimal, but how do you manage level matching, etc.?

"Sounds optimal, but how do you manage level matching, etc.?"

@hickamore 

If you're referring to gain matching different amps in a bi-amped setup, I do it with my McIntosh MEN2200 Room Correction System vis a vis its low/high pass filters/outputs as it allows me to adjust output gain between them. 

I'm sure there are all sorts of opinions on the right or wrong way to do this, but thus far it has worked quite well for me.