In-wall speakers tend to not have much bass because of the lack of cabinet volume and small woofer drivers. Due to this, more and more in-wall speaker companies are making in-wall subwoofers that are designed to fit inside the space between two studs and use a sound box to make deeper audio signals to provide a more powerful in-wall speaker experience, especially for in-wall home theater systems that don't have the room and/or the aesthetics for even a small traditional subwoofer.

Many designs, like those from BG Radia and Artison, feature vibration-free designs.

Most in-wall subwoofers are passive (as opposed to active, or powered) and instead come with external amplifiers that are placed in a rack.

Other companies that make in-wall subwoofers include Definitive Technology, PSB, and Totem Acoustic.

HomeTheaterReview.com's in-wall subwoofer reviews include:

Definitive Technology IWSub 10/10 in-wall subwoofer
PSB CW800E in-wall speakers and CWS10 in-wall subwoofer
Totem Acoustic Tribe 12-inch in-wall subwoofer