So the floor under the t.v. is concrete? If the base is tall enough, you can drill notches in the stud bottoms, run wires, install metal plates, re-install base. If it is glued, (required by manufacturer) you will probably ruin it on removal. Cut sub floor next to the I- joists, install 2x support boards with screws or nails from a gun.(screws won't vibrate and pop fasteners in the ceiling below) The joists have holes that remove with a tap. Screw flooring back on. Be safe, GBAR