I have an iMac running 10.6.6. When I listen to music through iTunes the sound has a lot of static to it. The problem seems to be getting worse and worse. I hear it both through downloaded songs and when playing CDs but I don't have any problems with the sound while playing video (either on iTunes or with the DVD player). The problem seems to be limited to music files only. In fact I just watched a DVD of The Who and if anything the audio was too loud. The speakers are external with a woofer. Someone told me to zap the PRAM which I did. It may have helped a little.