Okay, I've checked everything I know how to, but cannot figure this out- I'm only putting this here because what I'm hearing comes from the sub of my Logitech z-5500d setup. Often, when I plug in a USB cable, or touch anything metal to my case, I hear a "click" out of the woofer. I also hear it when I switch speeds on my ceiling fan. Or when the washing machine switches from wash to spin. (The fan only does it switching from "hi" to "medium," not from med to slow. Multimeter shows no faults anywhere on/in the case. Any electricians out there?