An audio distribution system comprises a plurality of individual signal conditioning circuits connected in series. Each circuit comprises a signal conditioning unit to which an audio input (13) is fed. The output from the unit is fed to a precision signal addition device. Each circuit also comprises a balanced line level input (11), which is fed to a balanced to unbalanced precision signal converter the output of which is connected to the precision signal addition device. The output from the precision signal addition device is fed to an unbalanced to balanced converter which provides at its output a balanced line level signal (12). As compared with a conventional distribution system, the system enables only one balanced line level input to amplification equipment eliminating any mixing or control means that equipment and obtaining the need for a conventional mixer.