Potentiometers are very common in audio amplifier systems. They are used to control the volume, bass, and treble of the output sound. Perhaps you have noticed that the modern audio systems are more digital and the electro-mechanical form of potentiometer is becoming less common in such applications. This project from Embedded Lab describes a stereo audio amplifier where the output volume is controlled digitally from tact switches. The main controller in this project is our StartUSB for PIC board that receives the user inputs from the switches and controls the output volume of left and right speakers through a DS1868 digital potentiometer chip.
Watch this video to see it in action.