Amazon.com: Audio Power Amplifier, 2x15W + 20W Hi-Fi 2.1CH HiFi Stereo Subwoofer Amp Home Bass Audio Power Amplifier Digital Amp for Auto Car MP3 MP4 PC Speaker(Black) : Electronics
6-1/2" 2-Way Bookshelf Speaker Pair and Hi-Fi Mini Amplifier Bundle
The benefits of a subwoofer in a hi-fi or home theater installation - Son-Vidéo.com: blog