Silicon it if you want a cheap fix, but once a hole is there, it will be weak there and eventually will tear more from use (at least from my experience). I have done the same and silicon'd it up but with hard use they ripped more over time.

If you want it done right you can call the manufacturer of the sub and explain what happened and they may warranty replace the sub for you, if not they can give you the info on the replacement excursion around the sub.