I have subs hooked up to a facotry 98 Accord Ex head, but when I turn the head off, an extremely loud noise comes from the sub, until the head is switched back on. I'm worried about my amp, but my install guy says there's no power source for the amp to connect into that will turn off the amp. Is this true or does he just want me to have to go buy a head? I like my factory head because I can use steering wheel controls, and it makes my car less of a target for break-ins. Thanks.