Pins on Audigy 2 ZS for Case Audio:

1 - Analog Ground
2 - Analog Headphone Out Left
3 - Audio Backpanel Mute -- short to ground to mute the backpanel (when headphones are plugged in)
4 - Analog Headphone Out Right
5 - same as #3
6 - Mic input from front panel
7 - key pin (shouldn't be there)
8 - VREF out -- voltage reference for Mic
9 - Mic in Mute -- ground when mic isn't plugged in, +12VDC when mic is plugged in
10 - Audio cable detect -- will be ground when headphones are plugged in (not normally used)

(This “might” work on other Audigy cards besides the ZS)