@ratso... I think if you wanted to do that, you should look at the sound card in your computer. I would suspect that a decent sound card, capable of 5.1 audio would have outputs for a subwoofer and three additional speakers.
I think, by design, B&W omitted the surround sound processing circuitry from their speakers.
I'm just guessing, but it seems pretty logical to me.
And it doesn't sound as if they're THAT weak in the bass department, seeing as, on the first page of the review, Clint had these two comments about the pros...
Unbelievable lows
Tactile bass