The members here seem to be very knowledgable and hopefully can help me. Excuse me if I go long, I want to give all information I can. When hooking my Compaq laptop up to my Yamaha power mixer(EMX 660) I get interference. The speakers pickup hissing and junk from the laptop. I have another rig where it picks up no noise at all. The setup for the problem is this... laptop and Yamaha power mixer pluged into Furman power conditioner. Gigaport sound card pluged into usb port and other end into power mixer input. speakers pluged into power mixer. The setup with no problem has a numark mixer, QVC amp and laptop pluged into furman power conditioner. Gigaport pluged into numark mixer. No sound problem there. Thanks for any help you can give me.