I, too, plan on a B&O surround sound system.  I, too, am unsure what substantial difference there is between the BL 7-4 and 10.  I see that the BL 10 has a slightly deeper bass response vs. the 7-4.  I take it that this is because the former has a greater cabinet volume.

As a general rule, I think it's best not to have drivers aligned horizontally due to differing distances from the drivers to the listener.

David

Hi thanks for the replies. I am now waiting for the press release for this new surround sound before making any decisions. Now I am going to start looking into projectors and electric screens. I know projectors have come a long way and are unbelievably clear these days. Does anybody have any rocomendations? Would b and o recommend a certain one? Also screens is there good ones and also ones to avoid? Chances are I will also be needing a lift for the projector so that it pops out of the ceiling when in use and back in when not. Again does anybody have any recommendations along with any to avoid? Thank you all in advance . Cheers

epson and jvc do some cracking projectors, b&o usually say sim2 for projectors,