“What if you think it's warranty, but an examination by the manufacturer finds you overdrove the speaker motor and it is fried?”
Easy. Nikon does this with their cameras. They pay for the shipping, but if they determine that it’s not a warranty issue, then the consumer has to pay for the repair and shipping.
There of course will be times when the manufacturer and consumer dispute whether the cause was abuse or manufacturer defect, but I’m going to assume the manufacturer knows their own product well enough to know.