How to play two audio devices same time

[somalisepi]

I want to play my xbox sounds and music from my computer simultaneously trough my headset, is this possible?

 

[americanaudiophile]

You would need to feed the analog audio from both to a mixer and connect that to the headphones. Something like this
http://www.parts-express.com/rolls-mx51s-mini-mix-ii-4-ch-mixer-with-headphone-output--245-044
You can adjust the relative volume of the xbox and pc to get just the mix you want.