Bringing the sub-bass, the Sonos SUB wireless subwoofer supplies the missing link in the Sonos line of superconvenient WiFi sound systems. Place it anywhere, even flat and under a sofa or bed, power it up, step through a few settings via computer, smartphone or tablet with the controller app, and there it is, instant gut punch! A pair of force-cancelling speakers positioned face-to-face not only sounds good, they eliminate cabinet buzz and rattle. Two Class-D digital amplifiers push the power. Compatible with all Sonos sytems. A gleaming high-gloss black laquer version ($699) is coming in June, with a matte black finish ($599) following up in the fall.