I have a amp hooked up It works perfect. I recently got an MTX 801D, I hooked it up and it didn't work. If you adjust the gain it will make noise, if you adjust the other knobs it will change the sound of it. power coming out the speaker output, no music. I'm running one Alpine R 12" 4ohm. Parrellel. I cut into the signal through the rear speakers of the car with a converter. Not the best way but with this car and its setup anything else would be a major operation. (Volvo S80).