A couple weeks ago my speakers reduced the volume and sounded crackled and blown when at a high volume. They haven't done it in a while until today. They do it when at high volume and only on the ipod input of my deck. It doesn't do it on the radio. it has happened multiple times today. Its not the speakers cuz it happened on the originals and now i have new speakers. I'm amping the speakers tonight and I'm gonna see if they still do it. Any idea whats causing it? The actual radio control volume doesn't change, just the speakers themselves.