There are some audiophile grade speakers made for in-wall and in-ceiling. I've heard in-ceiling Triad loudspeakers and they were excellent. Also, Mirage makes a series of in-ceiling omnidirectional loudspeakers with titanium coated poly mid/woofers and titanium dome tweeters.
Parasound also makes a full line of in-wall and in-ceiling loudspeakers and an in-wall sub.
Parasound also makes a full line of in-wall and in-ceiling loudspeakers and an in-wall sub.