Everything's great about my Mac Pro, except...

[benguild]

Even when an audio device isn't selected, there's a constant, noticable "BLAAAHHHHH" noise in the background.
Almost like a loose connection?

What really sucks is if I hook up my stereo and turn THAT up, it amplifies the music, AND that sound... so if nothing's playing that's all you can hear.

Clearly a defect, I'm not sure what to think about it. Anyone else having this problem?

 

[Sun Baked]

Ground loop isolator ... or whatever it is called.

http://docs.info.apple.com/article.html?artnum=86655

 

[benguild]

Oh okay, that's easy.

All of the audio outputs are doing it though... but I haven't tried the optical