Vandersteen 2WQ

I'm considering it to support my B&W N805. Will the crossover before the the power amp. degrade the sound in terms of purity, transparency, airiness, & palpability, especially without active preamp?
Without testing your specific setup, there's no real way to tell if the Vandy hookup will have a detrimental effect on your B&W's. However, based on my experiences as a long-time Vandy owner, and based on all the reviews I have read about the Vandy sub with non-Vandy main speakers, I'd guess that you will be pleased with the result. The hookup that Vandy uses between the main amp and the sub provides a way to balance the efficiency of the sub with the main speakers (I think the efficiency range is from 84 db to 92 db). Both of the Vandy subs (2W-Q and V2W) were reviewed in "Widescreen Review" magazine, and the reviewer stated the Vandy 2W-Q was the most musical and best integrated sub he has ever heard (he has 4 of them in his system). Both models earned nearly perfect 5-point ratings in all categories. There are to main differences between the V2W and the 2W-Q: 1) the V2W uses a 12" passive radiator in addition to the three 8" drivers; 2) the V2W accepts direct input from your pre/pro from either the line out jack or the LFE jack (which allows it be driven directly without the crossovers used in the 2W-Q). The V2W is about 3db more efficient than the 2W-Q, which may also be worth considering.
funny you just posted this. i just posted somethign about the vandersteen 2wq i just bought and am using with my old acoustat electrostatic speakers and they are fantastic. i got mine from randy at optimal enchantment in santa monica, ca (310-393-4434) and he can explain in excruciating detail why these subs are the ONES. if you live in the LA area you can stop by and hear these brats and judge for your lonesome. also, randy will lend you a demo if needed. people on audioasylum feel like randy and now i do about these things.