Which amplifier to drive B&W Nautilus 802?

Rahter than name specific amps, I'll describe the TYPE you need IMO: a good voltage provider, with good engineering for impedance tolerance from the amp. This means a very hefty power supply. So, an expensive amp:(

As to the watt rating... assuming you'll be listening at LESS than the 802s' reference efficiency (i.e.less than ~90,5db @ 2,83V on low passages), a SS rated at +100W A/AB class OR class A ~50W should do. High quality tubes should offer a nice sound. I would expect to need 75~100W.

The best is to TRY out a few models for yourself, however.

Accustic Audio

Accustic Arts

manufari,

Gregm gives you good advice. I happen to agree with him as that was my personal experience as a former B&W owner.I used to own a pair of the (less exalted) DM series & even tho I had them hooked up to my (German) Symphonic Line amps, they never really sounded their best unless I cranked up the volume. They had below average low volume details despite the Symphonic Line amps being high current amps. I think that this had to do with the xover component quality & topology.
Hence, look for a high current amp - not necessarily a high wattage amp but a high current amp.
If you can lay your hands on the oldie but goldie Plinius SA-50 power amp that should give you decent SPL assuming that you will listen at the 85dB SPL level. I'm sure that it can provide more SPL but I don't have a feel for where it will commence straining itself with the N802. Often I see Plinius SA-250, SA-102, Krell FPB-XXX i.e. the highest power level you can afford!, Rowland Model 10 & Model 12, Pass X350, Spectron Musician II driving the N801, N802 & N803 speakers.
I found that the cleaner the power amplification source, the better the B&W speakers sounded i.e. their sound muddies up very quickly as the quality of amplification degrades. FWIW. IMHO. YMMV.