I'm amazed that you've been able to power b&w 801's with tube amp(s), in that large a room, & have been happy with the combo. Even mono-blocs w/eight 6550C output tubes per side, is that correct?
IMO, you need to use big SS amps in a room that large, with either b&w 801's, or maggies. Or even in a smaller room. OR: get tube-friendly speakers..... nothing wrong with keeping the tube amps & getting speakers that match well....
(From someone who learned the hard way trying to power b&w M802's with tube amps.....)