Having lived with the N805's for almost 5 years now I like to add some observations gleened from lots of experimentation and equipment changes.
1. Take the grills off when listening. This does wonders for the width of the soundstage.
2. The more power (current) the better.
3. Very revealing of downstream equipment.
4. Use good mass loaded (heavy) stands that are coupled to the floor.
5. Better to bi-wire.
6. Sit with your ear level with the tweeter.
7. Spend a little time tuning the room. Damp the first and second reflection points.
8. Give them some room to breath; about 3 feet into the room is good.
When you get them set up correctly they really sing. My N805sig's image sooo good that I like to trick people into thinking that they are listening to surround sound. Anyway, this tread was about amplifiers and I've gotten side tracked.
Amps that I've used with great success with my B&W's are Scientific audio research labs MOS400, Aragon palladium mono's and aragon 8008BB.
If your going to do the surround thing then I would say try one of the 5 channel amps from the following manufacturers: Macintosh, Aragon, Rotel, adcom or sherbourn. I've only had experience with the Mac amplifier but I will be trying the Sherbourn 7/2100 in my rig next week. I'm getting the urge to simplify. I'm currently using 6 amps for seven channels.