Hi Guys

I have wanted to fit ceiling speakers for some time now but out living area has a concrete slab for the second story so there is only a 25mm gap between the plaster board and the slab . Everyone said you won’t get speakers to fit that space. I bought 4 Monitor Audio WSS 430  speakers that have a 50mm clearance. I made some frames from MDF to space out the speakers and glowed them to the ceiling l think they turned out good but getting the cables trough was a nightmare but we managed it in the end. 
So most things are possible if you think outside the box .

cheers

Good bit of work, that. Well done!