"What I meant was, I read that B&W recommends a certain "spec" not brand when using a speaker cable so as not to have the highs rolled off. Not sure where I read that, but seem to remember it. But you never see such specs when researching cables."
The last thing you have to worry about is rolling the highs off on a B&W. As far as specs go, I've seen them for cables. Not all manufacturers list them but most of the bigger ones do. Honestly, though, I don't really put a lot of trust in specs.