Sorry mate, AFAIK you'd need to downgrade to an ASUS DX XONAR as they version does have audio-out headers that you can plug your front case panel audio jacks into. Otherwise, you'd just have to keep switching it over via software and the jacks at the back, or plug the headphones into the speakers.
Core i7 4770k 4.2Ghz
Crucial Ballistix Sport LP 1600MHz 32GB
EVGA GTX 480 HydroCopper FTW
ASUS Xonar DX
Corsair Neutron GTX 240GB | Windows 7 64-bit
Apogee XT + MCP655 & Thermochill Triple 140mm Radiator
Corsair AX1200 PSU | Cooler Master HAF-X