Pioneer AVIC-Z1 Car DVD Player "making loud humming" Questions

...loud humming/buzzing sound comes on as soon as the car is turned on. I think the amp may have overloaded the system. Any thoughts? you might need a surge suppressor i think that what its called i had ...

Loud humming sound I am about to purchase a car that has an aftermarket MD-1040CMX Car DVD Player installed. When opening and closing the doors to the car, the video makes a weird, loud, humming noise