Okay I talked to all my comp sci friends they can't get this one either. I must go to my poor friends in elec engineering. To be honest I kinda just started using bluetooth headphones to get around this problem and the people living below me told me i cant use my sound system anyways (they get pissed easily) but I still want to get to the bottom of this. I refuse to say I “need help” because I am a very competent computer user. But this is a problem that I can’t get to the bottom of and goes beyond the scope of most the idiots I have talked to. That is why I am posing this question as a challenge since I know I will most likely just have to ignore it. I’m going to post all the details and maybe someone out there will humble me who knows what to do. The Situation: I have a Sony laptop (VGN-SR540G), an Acer P244W monitor, a Sony Bravia home theater speaker system. Naturally, there is nothing more I would like to do than use all three at once. However, when my laptop is connected to both the monitor and the sound system there is audio noise. Here are the details: The noise is a low frequency hum. (Sounds a LITTLE like this maybe not as low frequency and not as creepy sounding ) The video is borrowed from something else I didn’t bother to look at This noise occurs when my laptop is plugged in AND when my laptop is unplugged. The audio system has a two prong (ungrounded) plug. The monitor has a three prong plug. The laptop has a two prong plug. The audio system noise is there when the monitor is plugged in through the HDMI output AND when it is plugged in through the VGA output. Audio output goes through my headphone jack. Audio noise DOES NOT occur if I am plugging headphones into my laptop HOWEVER if I plug in my audio system to the laptop and then plug in the headphones to the audio system THEN you can hear interference through the headphones. Audio NOISE is MINIMIZED when LAPTOP SOUND is MAXIMIZED. In other words audio noise does not depend on laptop volume only amplifier volume. The noise occurs even if the laptop is muted I have tried a few “moving around the plugs” to deal with ground loop but it really has done nothing at all. The noise comes from all speakers not just the bass. If the monitor is not connected to the laptop then there is no noise. If the monitor is connected to the laptop there is noise. If the monitor is OFF but connected to the laptop there is noise. If the monitor is unplugged but connected to the laptop there is not noise. Okay kids have at it and tell me if you need more details.