Bowers & Wilkins DB4S subwoofer 

The Bowers & Wilkins DB4S is a high-quality subwoofer that delivers excellent sound for music and adds authentic explosive power to action scenes in movies.

The DB4S is an active subwoofer equipped with a single 10" driver, suitable for use with both the 700 and 800 series. With this app-controlled subwoofer, you can make all adjustments from your seating position, and the subwoofer integrates seamlessly with the main speakers. You can select which Bowers & Wilkins speaker is playing from the menu, and the subwoofer will immediately optimize its settings. This is a beautiful and high-quality subwoofer, both aesthetically and acoustically.