If your current speakers do not give enough bass depth or extension, a subwoofer can be a good upgrade option for stereo music listeners. However, most subwoofers are purchased by those creating a home cinema system - the subwoofer reproduces all frequencies below about 120Hz, allowing the surround sound speakers to concentrate on midrange and high frequencies. Almost all subwoofers are active, meaning they have their own power amplifier volume, phase and crossover frequency controls, to allow the user to tailor it's output to match the rest of the speakers and room.
Connect your subwoofer to your AV receiver or home cinema systems using a dedicated subwoofer interconnect cable which can be purchased in lengths up to 10m. In a hi-fi system, connect your subwoofer to your amplifier using good quality speaker cables and banana plugs.
For more information on the role of subwoofers in an AV surround system, see our "How to choose AV surround speakers" on our blog.