I had B&W 801 Matrix Series II, back in late 80's when they were just released, they were my first serious speakers. At that time I use to run them with Audio Innovations Series 500 amplifier (push-pull tube amp with 25W of pure class A power). I thought that was a very nice match at that time... hahaha. Had to sell them few years later as I was moving around the world for a while.
Since then I spent most of the time with full horn system (Altec) with SET amps (45), and also with d-class amp with Boenicke speakers.
I tried few d-class amps (Hypex, Pascal and Anaview) and to my ears the Anaview AMS1000 (2x170W 8ohms) sounded the best.
Last year I bought again B&W 801 Matrix Series II (in good condition and I installed a set of new crossovers) and for some time I was running it with d-class amp (Anaview AMS1000). I always had an itch to try Classe amp which is generally recommended for B&W 801 speakers so just few months ago I bought Classe CA-2200 amp. Wow, just wow... to me Classe CA-2200 amp is far better match than d-class for 801s. But I mean so dramatically better that I never had a desire to put d-class back in system... and now I have the best sound I ever had from my stereo system, and I've been in this hobby for last 35 years.
If you have a pair of B&W 801 Matrix speakers I would highly recommend Classe Delta amps (CA2200/CA2300 or CA monos). If you value balanced and neutral/natural sound than this combo is the answer. If this combo is good enough for Abbey Road recording studios than I guess it would be good for me too hahaha.
The one thing that I highly recommend you do to B&W801 speakers is to place them on Townshend Seismic Isolation Bars. This is the best way to decouple speakers from the room and your 801s will have bass like you never heard from them before... clean, deep, strong and very tight/controlled bass.