A variable low-pass filter (LPF) lets you tailor the sub's output to your existing speakers. By setting the LPF high (toward 180 Hz) you can fill in the bass for bookshelf speakers that may have extremely limited bass output, while a lower setting (toward 40 Hz) will supplement and perceptually deepen the output from larger, floorstanding speakers that have more of their own low end to start with.

You're getting more than just the basics here: the PSW100 comes with a phase-reverse switch for placement flexibility (to help align the crests and dips of the different sound waves when the PSW100 and your main speakers are in different places) and auto-on signal sensing for power conservation.

You can hook up the PSW100 one of 2 ways. In the first case, you can feed the sub an RCA-tipped line-level signal from your preamplifier or surround receiver. Using this method, your receiver can most effectively route the LFE (low-frequency effects) channel from Dolby Digital, DTS, DVD-Audio, or SACD surround programs directly to your subwoofer.

Alternately, you can run speaker cable from your receiver to the PSW100 and then from the sub's outputs to your front left/right speakers. Use of this method results in a more seamless transition from the subwoofer to your speakers since the signal arriving at your speakers has already been filtered through the PSW100's internal crossover (the variable LPF discussed above). If you plan to listen to stereo music with your subwoofer, this might be the way to go.

What's in the Box
Subwoofer, 4 screw-in wooden feet, and a user's manual.

Product Description
Powered subwoofers have become integral to any complete audio/visual system, particularly home theater. Normal speakers leave the very lowest frequencies unheard. Powered subwoofers fill in those blanks. For years, AudioSource has been the leader in providing quality powered subs at affordable prices. All include level controls and both speaker and line inputs and outputs. This model features a variable crossover from 40 Hz to 180 Hz, auto-on circuitry, and a phase reverse switch.