a suggestion that might prevent the cat from touching the speakers again;
when you see the cat interested in the speakers and he's coming near, play a sudden blast of 50Hz sound, like some dance music beat.
do that only when the cat goes near.
it should not take much time to be an effective deterrent.

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