Abstract: An encode/decode 5-2-5 matrix system is combined with a discrete digital, multi-channel audio system to expand the number of independently addressable output channels. One embodiment of the system provides additional output channels by matrix encoding the additional audio information into the rear surround channels of a discrete digital five channel surround system. The expanded channels provide additional center surround and left and right overhead outputs. The 5-2-5 matrix channel separation is improved by increasing the surround channel attenuation when no dominant surround signal is present in the input to the 5-2-5 matrix decoder. In a second embodiment the system provides a surround encode/decode system offering eleven independently addressable output channels.