subwoofer for B&W 805sig

Check out the Vandersteen 2wq. This sub is great, I used to own one, it increases the bass without giving you the excessive boom that so many subs create. I believe price is around 1200.

i have cdm-1 NT's (which i consider to be a slightly less refined / cheaper version of the 805 - similar portint, driver, tweater, construction, size etc) and i recently got a velodyne dd10, and found that it's quite versatile for both music and movies (and has multiple remote-able presets for them). it's room-eq settings, 3000 cycle-per-second servo sampler / control and general quality of driver and amplifier construction have impressed me quite a lot. i'd waited YEARS to pick the 'right' sub and i think this is it :)

I have read many places and come across many posts on other forums saying that the REL works very well with 805. I personally own the REL Strata III and am using it with Chartwell LS3/5a's and Paradigm Studio 40, not had any problem integrating either one despite the fact that both speakers are totally different. Besides, my understanding is that the reason folks buy REL subs is because they need not worry when they change the speakers since it is generally believed that REL's gel with any speaker you connect in the chain.

There may be others who might give you an insight into the ASW800, however, both being from the same company I think that they may mate well.