I concur with Abstract7, and will add to your consideration both the Theta Dreadnaught and the Meridian 558: both have the power to run the N803s and are on the richer High Freguency (HF) side: the Krells and Brystrons could be harsh on the HF. I haven't heard the ML, but the commentaries are toward a great top-end: they may be too expensive, though. Tube amps will not have enough bottom-end for the N803s (to be esoteric, though, bi-amping with Tubes on the HF and a Bryston or Krell on the LF would be spectacular.
For a lower cost, mid-fi solution, try the B&K 3220 or the 2220 monoblocks: I run the monoblocks, and for the money are excellent (but not in the same league as the others).
For a lower cost, mid-fi solution, try the B&K 3220 or the 2220 monoblocks: I run the monoblocks, and for the money are excellent (but not in the same league as the others).