I'm useing the B&W 803s with the KAV-400xi and it seems to be a very good combination (High-powered amp. w/High efficiency speakers). I find this Amp. to be very neutral as well as the 803s.
I've also heard this Amp. paired with SF Cremona, Krell Res. 2 + Revel F32, all combinations sounded very good to me, with the B&Ws edging-out on detail & imaging.