If you are not satisfied with the bass performance, I tend to believe the blame is not with RB-1080 nor with B&W.
I would look at RC-1070 instead. It is nice, but not in the same league with the rest of your equipment.
Rotel RB-1080 has one of the highest damping factors of all power amps -1000 (!). Even if due to speaker connectors/cables damping factor drops tenfold to 100, your Rotel power amp is capable of competently handling even the most demanding speakers. To use authomobile analogy, it handles bass the way BMW 850 handles Alpine autobahn. Effortlessly. RB-1080 is a gem for the money.
Also, consider upgrading stock AC power cables on RB-1080 and FMJ to better one. Even $10 Volex 17604 or 17605 makes a signifficant audible difference. Mains filter such as Rotel RLC 900 ($100-120 used) for digital end and preamp can also make signifficant improvement.
Just my .002