Meridian Hits the Wall
The Meridian P200z in-wall subwoofer fits an eight-inch active driver and eight-inch passive radiator into a three-quarter-inch depth. In a conventional subwoofer, that's not nearly enough space, but the dedicated amp (bottom) uses DSP magic to compensate. The enclosure is a nonresonant wood-metal laminate. Price tentatively pegged between $4000-5000.