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