If the impedance drops low below 20hz the speakers will be drawing a boat load of current especially at loud listening levels. Not only would you be wasting a lot of useful power but its also a good way to clip the amp as well as overheat and put a receiver into protection mode. This would not be good for the longevity of the electronics and/or speakers.

I’m armed and I’m drinking. You don’t want to listen to advice from me, amigo.

-Max Payne