CA Series Audio Controller/Amplifier Overview Russound's CA 6.4 and CA 4.4 are integrated distribution amplifiers capable of playing up to four different sources into multiple zones, which are typically individual rooms. The CA 6.4 is a four-source, six-zone unit while the CA 4.4 can handle four sources and four zones with the added features of pre-amp outputs, telephone mute control and a 12 volt trigger. Both CAS are also expandable to several zones by using the included IR link adapter. Both the CA 6.4 and CA 4.4 are simple to install and to operate yet offer amazing flexibility and control. The CA Series offer a wide variety of optional accessories, including attractive backlit keypads, programmed, learning and standard remote controls, doorbell interface, doorbell telephone interface system, paging module and telephone paging module. Russound offers a complete line of CA accessories for virtually any need.