I have a alpine iva-203 headunit and a alpine mra-d550 amp running some JL zr components. I have a fiber optic cable and ai-net cable linking the two. I cant get any sound out of the speakers. I turn on the optic cable on the headunit. I was told that there should be some sort of red light coming out of port on the back of the headunit once its turned on, is there any truth to this? Cause I don't have any red light coming out. Any ideas on what the issue is ?????