Take a look at the Mirage HDT and the Incognita series. Both line ups combine to blend box, in-walls or in-ceilings.

The mounting system is considerably more advanced than most in-walls, incorporating sophisticated and patented damping systems that enable the system to match box speaker performance.

You can see it here:

www.miragespeakers.com

Click on Incognita and check out the HDT box speakers as well.