Conclusion
The B&W Signature 800 is a great speaker—perhaps the best I've ever heard at home—and was a continual delight to listen to. With the right supporting cast and under the right conditions, it has a potency, resolution, and transparency, from the lowest through the highest frequencies, that are unsurpassed for a speaker of domestically acceptable size.
Scuttlebutt on the 'Net suggests that the S800 is too bright, but I didn't find it so. What I did hear was an unremitting clarity that laid bare any shortcomings in source material or components. On the one hand, this meant that the S800 let me hear exactly how the engineers mixed and balanced every recording I played. On the other, it served as a constant reminder that most recordings are, intentionally or not, engineered to redress the flaws of less accurate speakers in less than optimal listening rooms. The Signature 800's ability to reveal this is one reason that it, like B&W's Nautilus 801 and 802, is suitable as a studio monitor—which may mean that it's too demanding for any but the most scrupulous home installations.