I need to make this clear, the humming is proportional to wheel speed NOT engine speed. When the vehicle is stopped, sounds crystal clear even while engine is running. As soon as i start moving it thumping until its a steady hum when i go fast.

Using stock radio with a schoshe LOC grounded to the wire harness behind the head unit. Sound stops when RCA is disconnected from LOC. Amp has good ground and power wire is ran on opposite side of the car. Any ideas?

 

The problem seems to be very tedious one. First you need to check all the parts of the sound system by proper technician, where you can get as to where is the exact problem going. Ne you can try various things like dynamat alternative, which can surely give a peoper solution.