check the internal mixer in your operating system, within windows youd goto control pannet, then click on sound and audio(or whatever) in there click on volume, then "advanced"......once the mixer opens click on file, properties, and uncheck everything it lists that you dont need, then look at the mixer, and lower the levels you currently aret using while you record(cd player..whatever)
sometimes when these are up full they make a hiss sound, i think this will solve your problem, i know i ran into it a few times...