What were they thinking about??

The plug at the end of the power cord on the crossover for my Infinity Beta speakers has only two prongs. Both prongs are the same size and are not polarized. I sometimes get an annoying thump when I touch my rack or another piece of equipment on the rack.

Is there a way to retroactively have the power cord have some sort of polarization or grounding? Sorry, I know nothing about electricity and wiring...but it seems this shouldn't be too hard to do for a skilled person that repairs audio equipt. Does anyone have any suggestions how this can be fixed? Any recommendations for a place near Los Angeles, CA that I can take the unit for a power cord update?

thanks........mitch