I've read and researched this a ton today trying to figure out what exactly the problem is. The setup is this, I have a cheaper surround sound system. My TV, Xbox 360, and laptop are all hooked up to it. Now, I'm definitley getting some EMI/RFI line noise because at first I was hearing a slight buzzing noise and picking up radio stations through the speakers, even when the unit was turned off. I moved the surge protector that the TV, Xbox, and Surround Sound unit are all plugged into away from the unit and the noise stopped when I switched to the TV or Xbox. But, when it is set to use the laptop, I still get the buzzing noise and radio station. I've moved the cables around, unplugged and shorted the RCA cables, I even went to Radio Shack and bought a couple Ferrite Data-Line Filters. All to no avail. Now, I'm thinking that the grounding problem is with the laptop's power supply, because the only way I can get the noise to stop is to unplug the power suppply from the laptop. If it's running off of straight battery power with the same RCAs and setup up, just not plugged into the wall, no noise. But that's obviously not very feasible. I don't know what else to try. If this is hard to understand, I'll draw out a diagram or w/e. Any help, please?
A different socket doesn't matter, it needs to be plugged into a different leg coming from your breaker box. To see if this theory is correct, take an extension cord and plug in your laptop from the furtherest room available from your setup. If this works, in general, you probably have a grounding problem in your home wiring.
If it doesn't work, your laptop may be generating the tone (humming noise) from within when charging. Not much you can do about that one. It just means the engineers did not do their job when designing your laptop, to keep feedback EMF away from other electronic parts.
