I have hooked up a new (for me) set of powered speakers to my laptop. The speakers are Monsoon 500 series, a three way system. When plugged in they hum, noticiply (to me). If this was a normal stereo setup I would look for a grounding problem but as they are simply powered speakers plugged into a laptop, I do not know how to get rid of the hum...The hum is a constant volume independent of the volume setting.

Any ideas would be welcomed.