The Rotel 1090 is a very nice affordable choice to match with N803's. The 1090 is very good on the top end. It is detailed without a hint of shrillness. B&W produces a wonderful mid-range, to my ear, and the 1090 does nothing to detract from it. At the bottom end the Rotel produces a tremendous amount of base, however, the weakness of the 1090 lies in this area. The base it produces is not the ultimate in being tight and quick. It has a tendency to be toward the soft/slow side. Which is not to say it is sloppy (far from it) but in comparison to an amp like Krell. I know this is true with speakers larger than the N803. I suspect it would be less true with your speakers. On the other hand, you can listen to the 1090 all day long. It is very easy on the ears.
Krell is a different price category. If you move to that level I suggest you listen to Simaudio. It mates wonderfully with B&W.