A distorter is provided that allows a musician/sound engineer to affect the operation of a distortion circuit using a second musical instrument or a sound modifier, enabling the musician/audio engineer to vary the behavior of the distorter in real time. The invention enables a musician and/or sound engineer to achieve sounds and effects that are impossible to create using conventional distorters. The invention enables a user to provide a primary audio signal representing a musical instrument that is to undergo audio signal distortion; and to provide a secondary audio signal representing a sound modifier or a second musical instrument that is used to modify psycho-acoustic and/or musical effects of the audio signal distortion. An output signal is produced having substantially non-clipped parts for conveying the sound of the musical instrument, and having clipped parts for conveying psycho-acoustic and/or musical effects responsive to the second musical instrument or the sound modifier.