An electronic musical instrument incorporates at least two tone signal outputs and controls sound image localization of musical tones in accordance with localization data by changing the levels of at least first and second tone signals provided, respectively, to the tone signal outputs. The instrument includes a tone signal generator for generating a generated tone signal and an output control data production circuit receiving the localization data and providing tone signal volume data and a selection signal. A tone signal output level control receives the generated tone signal and provides the first and second tone signals to the tone signal output. The tone signal output level control has a multiplier for altering the generated tone signal responsive to said volume data to provide one of the first and second tone signals. The tone signal output level control provides a signal corresponding to the generated tone signal unaltered by any multiplication as the other of the first and second tone signals. The tone signal output level control has a pair of selectors responsive to the selection signal for providing one of the first and second tone signals to one of the tone signal outputs and for providing the other of the first and second tone signals to the other of the tone signal outputs, thereby to control sound image localization of the musical sounds of the electronic musical instrument.