The summing cable can be used to combine a stereo unbalanced signal into a mono unbalanced signal. The AA-YSUM features a 3' (1 m) cable with two Male RCA connectors, summed together via internal resistor network into a single three position Phoenix/Euro Style connector that will match input and output impedance of most audio equipment.The AA-YSUM cable is a basic solution to a common problem faced in the commercial install world every day. Often, there are not enough stereo summed inputs on a mixer amplifier for playback devices such as CD, DVD, tape players, or DSS receivers. However, in many cases there are additional mono mic/line inputs available on the mixer section.With the use of an active summing box or the AtlasIED AA-YSUM passive unbalanced summing cable, you can utilize the open inputs of the mixer to meet your installation requirements.