I mention all that stuff because I have no idea what is really to blame here.
I noticed, with headphones (and presumably with any other output devices, such as my speakers) I was getting noise in my left channel. I figured it was this old Ensoniq AudioPCI (which I tend to call a SB32PCI, right or wrong) going out. Weird thing was, the noise was vaguely distinguishable as whatever was playing in XMMS, but I’d hear it even when I muted the master mixer, and most everything else. How could I be picking up audio signals… that were only in the card, and presumably not even hitting the DAC (if I understand how these things work)?
For fun, though, I popped up the GNOME volume control applet, enabled every single control I could in Preferences, and started muting and clicking on all sorts of things. Imagine my surprise when, by unselecting “IEC958 2” the noise magically went away. Apparently, IEC958 is S/PDIF. Next weird thing is… I don’t think this card supports digital output.
Very much thanks for your information!
It solved the same problem on my ES1371 on FC4 too!