Yamaha YST-SW315PN 10" Powered Subwoofer (Piano Black)
With 250 Watts of power and a multitude of features, the Yamaha YST-SW315 will bring room shaking cinema action into your home.  Advanced YST-II and QD-Bass technologies give this subwoofer deep bass without sacrificing clarity and accuracy.  The continuously variable high-cut filter lets you match the subwoofer's output to your other speakers and to room acoustics.  A convenient signal sensing circuit detects when an audio signal is present and switches the power on or off as needed.