Abstract: A multi-zone audio distribution amplifier system includes positions for several stereo amplifiers which may be used as modular and cascadable amplifier units. The system is enclosed in a housing having a front panel with windows for exposing a set of led display circuits on the front side of the housing and easy access to the modular units on the rear side of the housing. Each modular amplifier unit includes a printed circuit board for an amplification circuit, a heat sink, and a loop-back port for cascading the amplifier units. An interface board includes support for the display and edge-connector receptacles for receiving each printed circuit board edge and for providing power to each of the amplifier units. Each amplifier unit is operable independent of the others, and the desired amplification may be selected by electrically cascading the amplifier units via the loop-back ports.