Why not get a pair of Opticon 6 mk2? They're the best speakers dollar for dollar that we have ever heard, and will have a similar sound (but better) than the dual Vokal setup you have going.
Given how you are using the system, I would also strongly recommend switching that Cambridge unit for a home theater receiver of some sort so you can keep one of your Vokals and use it as a center channel. Unless you are sitting locked into a sweet spot, watching shows/movies without a center channel is hugely compromised if you are in any way out of the sweet spot.