Sonos' Sub, the latest addition to its wireless premium sound system, is now on sale for $699. The subwoofer features two class-D digital amplifiers, a pair of force-cancelling drivers, and is ready to sync with the company's amplified Play speakers and Connect:Amp with the push of a button — unamplified Sonos Connect owners need not apply. The system's Digital Signal Processing technology claims lossless audio quality, and sound equalization is processed automatically to properly balance levels between your other Sonos components. The premium black gloss Sub can be ordered now, with shipments expected to reach customers as early as July 30th. If you'd prefer to save some money, a black matte version is expected to be available this October for $599.