First and second sound channels are provided for processing audio signals. Each sound channel includes means responsive to a D.C. control voltage for controlling the volume of the audio output signal of the channel. A volume control potentiometer is coupled across two terminals of a source of supply voltage and a D.C. volume control potential is developed at a tap of the potentiometer. The volume control potential is applied to a control electrode of a controlled current path. The controlled current path includes the parallel combination of a first voltage divider and a second, variable voltage divider. A tap of the first voltage divider is coupled to the D.C. control input of the first sound channel, and a tap of the second voltage divider is coupled to the D.C. control input of the second sound channel. By adjusting the second, variable voltage divider, the control voltage provided by the second voltage divider may be set to equalize the D.C. volume control characteristics of the two sound channels.