Distortion+ M-104, distortion plus, m104 This little yellow box is responsible for those great distortion sounds heard on so many classic recordings. Set the Distortion control low and crank the Output knob to drive the front end of your amp for cool blues tones, or max out the Distortion knob for the tone that made Randy Rhoads famous. There still isn't any distortion unit on the market that sounds like the Distortion+.