A15PRS reverses the phase (polarity) of balanced audio signal. Typical use applications include correcting polarity reversal caused by a wiring error in a microphone cable, connecting an unbalanced high impedance microphone having the hot signal on pin 3 to the input of a mixer that requires the hot signal on pin 2, and reducing phase cancellation/comb filtering between two signals that are of opposite polarity. An in-line switch permits instant selection of either normal or reversed polarity for comparison purposes.