Check the volume on your computer. If any of the various volume controls are really high, you are going to get noise. That also means you probably don't have an actual sound card, but are using the motherboard's built in chipset. Which is OK going to computer speakers, but will never sound quite right on a higher power stereo. Just do what I did and buy a good soundcard that is designed for multi-channel output and it will perform 110% better.