A method and system for selecting a signal from a plurality of signals received by a component in an AV system. An identifier is added (106) to a signal in dependence on the signal being generated by an active component of the system. For each received signal containing an identifier, one or more parameters of the identifier are determined (116), such as the start time when the component became active, or the address of the component. A signal is selected (124) from the plurality of signals received according to the determined parameters and optionally with reference to a relevant parameter such as component address sent via a separate communications channel.