I don't think it's essential to get a rear center that matches the surrounds, although it would be nice (unfortunately all my experience with the 1050 involved identical surrounds and rear center, so I'm not real sure what difference it might make). Two speakers (both 8 ohm) can be connected, and the manual even has a short blurb on the subject.

------------------
gonk -- Saloon Links | Pre/Pro Comparison Chart | 950 Review