Here is a link to the Radio Shack Ground Loop Isolator, currently priced at $16.99US:

Ground Loop Isolator

Follow the directions, don't forget that you will need an adaptor that connects from the laptop's earphone jack to the RCA connector on the Isolator and that you may need adaptors for the other end where you connect your amplifier system also.

This should solve the ground loop hum problem.


--Mac