Take advantage of the new USACi Class STREET BEAT
The SUB16 applies a combination of equalization, low-pass and subsonic high-pass filtering, automatic gain control and broadcast-type bass modeling. Its aim is not only to enhance the different flavors of bass, but also to offer control and protection.
I have the 9v upgraded version without the remote. Specs and info found here
http://www.altomobile.com/html/sub16.html

$200 shipped
The SUB16 applies a combination of equalization, low-pass and subsonic high-pass filtering, automatic gain control and broadcast-type bass modeling. Its aim is not only to enhance the different flavors of bass, but also to offer control and protection.
I have the 9v upgraded version without the remote. Specs and info found here
http://www.altomobile.com/html/sub16.html

$200 shipped