ABSTRACT
There are only two electrical output terminals for an unbalanced output, signal and ground. Adding an opamp inverter to make it a proper balanced output costs little more, especially if there happens to be a spare opamp half available, and it sounds much better in the specification. The quickest way to measure normal output impedances is to load each output as heavily as is practical and measure the voltage drop compared with the unloaded state. A ground-cancel output or a ground-compensated output allows ground voltages to be cancelled out even if the receiving equipment has an unbalanced input; it prevents any possibility of creating a phase error by miswiring; it costs virtually nothing except for the provision of a three-pin output connector. In a balanced link, the CMRR is a measure of how accurately the subtraction is performed at the receiving end and so how effectively ground noise is nulled.
