I'm mounting some klipsch 5800 in wall speakers in my basement walls. They are framed with 2x4 with a 1inch gap between the back side of the stud and the concrete wall. There is no insulation in any of the walls. Should I seal the gap between the stud and concrete with say, expanding foam to create a single cavity and maybe add some fiberglass insulation below and above the speaker location?Also maybe provide a barrier between the insulation and speaker area with some cardboard? What size box area with-in the cavity should I leave for the speaker? Is ther a calculation? Acoustics? Boominess? or should I do nothing and let the whole wall act as a chamber? Suggestions or experiences please. I have a drop ceiling (8ft)and the room is 20x40