The Extron ASA 131 Audio Summing Adapter is a convenient, single-cable solution for combining two-channel stereo audio into a mono audio signal. It is ideal for summing stereo signals for use in mono PA systems in churches, halls, arenas, stadiums, and other environments where stereo signals would result in cancellation. Because it is a small and passive device, the ASA 131 is especially useful in systems where power and space are limited.