pwhit

I am buiding a home theater with the speakers built into a wall cabinet on the sides and under the screen. Using matched set of RF 3, main, center, sides and sub woofer. The subwoofer will be placed in the lower left and I may add one on the lower right. The mains are above and the center under the middle of the screen set back a bit. I am using grille material on the cabinet doors and positioning the speakers against the grilles. What is the best way to position the subwoofer. The cabinet box size is roughly a 28" cube. Should I line the inside of the cabinet box with acoustic material. Thanks