Luxman M-900U in bridged mono or McIntosh MC1.25kw with B&W 800 D3

I know this is not exactly what you are looking for, but I have McIntosh MC 611’s driving B&W 802D’3. One step down from you. I previously had a Classe 2300, which is a very good stereo amp. I found the McIntosh to sound slightly on the warmer side, but very dynamic, clear, and detailed, Bass and mid range are fantastic. Highs are dynamic but not bright or harsh. I know many say McIntosh is soft and romantic, but I would not describe the 611 that way. I think maybe the newer models are voiced differently from prior models.

Mac and B&W has always been a synergistic combo. Mac warms up the speakers which can be a bit incisive. OTOH, I think Luxman makes some of the best sounding equipment out there. Can't opine on bridging but I would be surprised if the 900U, by itself, is all you need. 

Luxman in stereo..that's my vote 

My error.

I meant to say about the Luxman:

"I would not be surprised if the 900U, by itself, is all you need."

The McIntosh amp is going to sound very nice and can sound special if paired with a high resolution speaker (such as the B&W D3). However, the McIntosh has a laid back presentation in the mids and highs. While it can sound very nice, it may not be exciting enough for your tastes.

The Luxmen, on the other hand, is a very high resolution amp but also has a very full sound in the midbass and midrange. This amp would be much more transparent and neutral when compared to the McIntosh.

Depends on what kind of sound you want.