i had the same with my logitech x-530 speakers at first the were so shit and not worth the £45.. making popping noises every so often, humming noise if the speakers were turned down/too loud and stupid foreign interference. but it seems now this has all gone away apart from the occasional pop, just give it time. i did however look it up at the time, it something to do with "grounding" which is a process taken during the manufacture of the speakers i think. so your speakers may have poor grounding like mine did, if your lucky it will go away however its worth searching for existing problems similar to that on the net. depends what make the speakers are, there may be a forum of such that you can ask about. hope this helped