Well...the issue is in one of two places. The head unit or the wiring to the AMP. Is the wiring to the amp rated to handle the size you are pushing? What is the gauge of the wire and how is it grounded? Second, I've had my protect light come on when the line level in is too high. So if you have an input knob, I'd turn it back to less than 3/4 of full. Otherwise, I'd see if I could get my hands on a different head unit, or have a buddy try out the amp in their car. But 3 amps and the same problem...it definitely isn't in the amp.