My dad recently gave me his old car and it had the Mac daddy setup installed. About a month later my sub would fade in and out consistently every couple of seconds. I went to my local car stereo store and they put one of their subs in and it had the same problem my original sub had. So now I'm stuck. My dad has a sound stream picasso Nano pn1 6500 under the drivers rest and a Rockford Fosquate t600-4 behind the back row seats. The sub was a sound stream 12 inch in a slim box. Any idea what I need to fix my problem since it isn't the sub? And why do I have two amps? On for sub and one for stereo?