I have seen stereo systems that have 2 or 3 amps going to one sub. How do people do that? Do the amps daisy chain together to double or triple the power and then only one set of wiring goes to the sub? Its only in crazy SPL set ups where Ive seen this but it peaked my curiosity.

 

As long as they are all putting out signal exactly in phase and nothing stupid is done with the connections, it could be perfectly fine. Potential for disaster is pretty high, though.