I suggest you look at the various dipole and tripole surrounds made by M&K. I think the M&K tonal balance is similar to B&W's, and they should make a good match. (If you look at my system listing, you will note that I am using M&K SS-150 THX tripoles with my Vandersteens.)
The M&K web site contains good information about their various models. Here's the link to the page describing their surround speakers:
http://www.mksound.com/surround_speakers.html
The M&K web site contains good information about their various models. Here's the link to the page describing their surround speakers:
http://www.mksound.com/surround_speakers.html