Does he want to apply it like wallpaper? If so, anything less than a heavy felt or carpet will have no effect at all. Does he want to stretch it over foam? Then it needs to be thin and open.

What does he mean by 'enhance'? If he means it will cut down on reflections and reverberations, then it has to be coarse and dense or thick foam. I spent much of my life as a recording engineer and designed recording studios and control rooms. If he wants to tinker with the sound, that's cool. But I'd recommend doing it in a way that's easily removed without doing any damage. Because a year from now...

I just bought new speakers and amp and I'm moving stuff around and experimenting with the new surround sound. Audio is still fun even though I'm not in the business any more.

Thanks! This helps. Yes, my husband loves his sound system!

If that is what he wants do the fabric on removeable panels it is almost impossible to get off drywall. There are actual panels you can buy that do exactly what he wants

Thanks!