at zero, you might be very near the clipping point.

damage is cumulative for speakers if you overdrive the amps.
the best thing to do is to have more power than you need, then you will never clip the amp output.
the M80's can take a lot, if the amp does not go into clipping.

See: http://www.blu-ray.com/community/gallery.php?member=Gelli
or: Axiom Gallery