To take a step back for a second, you're more likely to have success if you first match the speakers to the room and then match an amplifier to the speakers. You seem to be trying to collapse these two separate steps into one. Not that it can't be done, but it greatly limits your options. In other words, why are you so tied to your amp?
If the emphasis is on coherent sound you might also consider the larger coaxial designs from Altec (Great Plains Audio), the big classic styled Tannoys or the various Phy based speakers. They are all very efficient and like tubes.
If the emphasis is on coherent sound you might also consider the larger coaxial designs from Altec (Great Plains Audio), the big classic styled Tannoys or the various Phy based speakers. They are all very efficient and like tubes.