Regards of what the OP and the owner have going on. From one consumer to another, If I was to install a amplifier in that matter.. Run it like that for weeks. Then finally decide to install it properly, only for it to finally fail on me. The first person I would have to point the finger at, would be myself.
But, I will say this, if the owner does get this fixed at his own expense. That move in it's self, would have to put his CS at a " GodLike " status. Then he should change is motto to " You break, we buy ". LOLlipop