Martin,
Sure. It’s not a problem with the space above with ceiling speakers. They actually are designed to work with a box design called `infinite baffle.’ That generally means that the back doesn’t have to be enclosed and if it is it should be greater than 5 cu. ft.
Take a look at these for a recommendation.
> Name :
> Martin Hayes
>
> Message :
> I have a false ceiling with approximately 6 feet of empty space above ceiling. I`m interested in a surround-sound speakers system composed entirely of ceiling mounted speakers. Will they sound okay with so much empty space above them?
>
>