I just recently upgraded my speakers from the B&W CM2 (Concept 90 speaker from the late 80's with a series 2 Matrix design) to a pair of PMC OB1's. My associated electronics are a Rotel RMB1075 amplifier along with the Rotel 1098 pre-processor.
I've been tweaking around with cables a great deal lately and really recommend the Audience Au24 speaker cable (provided you can stretch your budget a bit since I think they would be just over your $500 limit). I find the Rotel/B&W combination can be a bit on the bright/analytical side. The Audience Au24 can really add an injection of warmth and smoothness to the sound.
I know the Audience Au24 is an expensive cable (and perhaps outclasses the rest of my system) but in my opinion...is simply an amazing cable.
Tony