I got a free set of speakers and subwoofer last weekend(hahaha now i know why). Every few minutes, a loud "crackling" noise comes out of the speakers for about a half of a second. The speakers are "Boston Digital BA7500G", and this is how they are set up on my desk: The subwoofer is actually on the floor right now. could it be a bad cable, or something else that would be easily remedied? or should I just junk these things?