my flatmate and i have been trying to hook up a laptop to the tv in the lounge which is working fine in the pioneer csx-c502 receiver. This works fine using a 3.5mm to duel-rca adapter and svideo to composite, until the power adapter is plugged in, and then the speakers start hissing. ive tried this on 3 different laptops (different brands as well). ive tried separating the power cable from the rest to no success. any suggestions on how to prevent this occurring?