There's probably no addition to a home theater or car audio system that produces as much boom for the buck as a subwoofer. It can make the entire system sound better, and for good reason. Installed properly, a powered subwoofer system eases the burden on your main amplifier. Getting the best bass reproduction from your subs may take a little tuning, since the acoustic impact of your listening space is crucial to the performance of any audio system.
Speaker location, listening location and even room furnishings can affect how bass frequencies perform. Low frequencies are omnidirectional, so the location of your sub is less critical for stereo imaging than main or surround speakers. This may give you multiple options in your listening area. Nevertheless, small changes in location may have an impact on how bass is heard at your listening position, so try different locations if you can.
While it's sometimes possible to connect a subwoofer to the main speaker terminals of a home theater receiver or car stereo, this usually won't give the best results. Most contemporary audio equipment will have dedicated sub support in the form of a jack labelled "Sub" or "LFE," for low-frequency effects. Using this jack allows your receiver to work in support of the subwoofer. Receivers equipped with calibration features will optimize your bass only when the dedicated subwoofer connection is used.
Isolating your subwoofer can produce dramatic improvements in bass clarity. When the sub transfers vibrations through the floor and walls, the room itself becomes part of the low-frequency reproduction system and chances are, it's not going to do the job as well as your subwoofer on its own. Subwoofer isolation pads can be purchased or fashioned out of high-density, closed-cell foam. This can be a solution when you have only one spot for your sub, for space or appearance reasons.
Choices for car audio subwoofer location are limited. While under-seat systems are available, trunk-mounted subs are most common. The key to great bass response requires matching the sub's amp with the main receiver. Both the subwoofer amp and the receiver may have filters, crossovers and bass boosts. Be sure that all are turned off when you start balancing your amps. Using the subwoofer's features will probably give the best results, though you can try the receiver's settings too. Use the sub or the receiver, but not both at the same time, which will likely degrade bass performance.