I've noticed noise when I share a dual outlet, yes, but it depends on ther way the outlet is constructed, I think. They share the same incoming AC, but the outlets should be separate from each other. I had a dedicated line installed to our home office for the PC from the electrical panel, and it's a quad outlet. I have the UPS for the PC plugged into one of the outlets, and on the other pair I have my audio equipment's power conditioner plugged in. Everything in my audio chain is powered from the Furman conditioner, and this way I've got no line noise or interference. Going old skool (lol) I've shared outlets with a computer and audio equipment in the past, and yes, I've definitely heard noise like easy's mentioned. Before I had any power conditioning or fancy power lines run, switching to separate outlets pretty much took care of the problem. I still had noise if I had all audio on one outlet and all PC on the other in a dual outlet, like you mentioned, but the wiring and electrical stuff in genereal at that apartment was pretty old and cheap, so I'm not suprised.