Have you tryed adjusting your "Line In" volume? Double click the volume controls on your task bar. Check the volume for your line in. It could be that it's set to high, or possibly but less likely, to low.
I get an audio hum when transfering music from tapes, LP's, or any source to my computer. I am using XP and the Polderbits recorder; the audio cable is from Radio Shack. I've tried routing the cable in several paths, but its still there. Thanks to anyone who has any suggestions to get rid of this annoying hum.