There are only two electrical output terminals for an unbalanced output—signal and ground. However, the unbalanced output stage in Figure 21.1a is fitted with a three-pin XLR connector to emphasise that it is always possible to connect the cold wire in a balanced cable to the ground at the output end and still get all the benefits of common-mode rejection, if you have a balanced input. If a two-terminal connector is fitted, the link between the cold wire and ground has to be made inside the connector, as shown in Figure 20.2 in the chapter on line inputs.