Line noise?

[markp]

Not sure if this is a Winamp problem, but there seem to be some pretty savvy people on this board, so any and all help would be appreciated.

My computer is hooked up to my stereo via the 1/8" headphone output on my laptop. When I am playing MP3s in Winamp, I get pristine sound with no interference or line noise whatsoever. However, when I am NOT playing any music, I get a weird low-level buzz that sounds kind of like line noise or interference. If I start another MP3 then it goes away, but this is annoying me because I like to fall asleep to music, and once my playlist ends, the buzz kicks in.

When I'm home, I get around this by cueing up an MP3 and then pausing it (no matter how long it's paused for, I still don't get the noise), but it'd be nice to get rid of this problem once and for all. So: is there some setting I can tweak in Winamp or with my sound module (a SigmaTel audio or something like that) to eliminate this buzz permanently?

Thanks,

Mark