803N power Requirements?

I have used a Krell KAV-500i (250 wpc integrated) with excellent results. I have also used its smaller brother, the KAV-300i (150 wpc) with good results too. These speakers DO NOT require tubes due to their relative sweetness. My feeling ( and that's all it is) is that a good tube amp such as a CJ Premier 11a or an ARC VT-100 should do a great job on these speakers.

B&W voice their speakers with Krell.
Buy as much power as you can afford.

If you had really read the N803 review in Stereophile, you would have noted that Sam had great results with the Musical Fidelity A300 amp.
My own experience with the A300 driving a pair of N804's suggests that the match is a good one, and that the A300 is much better than it's budget heritage suggests.
HOWEVER, I have run the N804 with Krell and various other amps as well. IF you can afford the better amps, DO IT! you will be rewarded. IF you have to skimp on the amp for now, I would suggest something in the realm of the A300 as the minimum benchmark.
I have heard the Nautilus series sound pretty poor in at least 2 circumstances, so, be warned, a poor amp/source/cable match will result in a screechy up front balance that will leave you wondering why you ever bought them.

Bigpoppakrell, so what amp you think is the best to drive the nautilus speaker, I have a 804 and looking to upgrade.

Chazzbo,
I have not heard the Rogue or Cary amps. However, your choice in amplification will depend on the sound you wish to generate from the n803's. The Nautilus line,in my opinion, allows you to hear quite clearly what your upstream components sound like. These speakers play clear as a bell and are extremely neutral. Your electronics will dictate everything. Remember though, the n803's can handle very powerful passages with ease. But with a low power amp you may not have enough juice to get the full effect of this. My recommendation is to try to get an audition of the BAT vk 500 or possibly a Plinius sa-100 or 250. You'll be able to achieve power and depth and delicacy at the same time. By the way, I own the 801's. I hope this response was helpful.