Well B&W do in-wall hidden speakers -
as explained here, which should sound as good, if not better than the B&W MT-30. There are lots of other good in-wall (or in ceiling) speakers available. I'd recommend looking at the KEF or Monitor Audio websites to see the sort of thing available. You will also need a sub-woofer, and Velodyne do some pretty good ones.
A word of warning, going in-wall or in-ceiling will increase the cost considerably and you need to factor in the whole placement issue as once done, you can't just move your speakers a bit. Get a CEDIA specialist to help you / do the work, or spend a lot of time researching it yourself.