No Sound

My old 500X has lost the sound.

Nothing, from any source. Not from a CD or a mp3 off the drive and no
windows sound.

So far I have done the following,

Made sure the speakers had power and were correctly installed. I could
hear sound from the speakers when I unplugged one of the cords.

Re-installed the drivers from the Restoration CD.

Unseated the board and checked the contacts and put it firmly back in
place.

Did a repair using the Restoration CD.

Made sure that the "mute" box wasn't checked anywhere I could find
one.

Nada, nothing helped.

Anybody want to make a stab at this?

Just realized that the cable attached to the sound card is actually a
Firewire port. Makes me wonder.