how do i get audio from my xbox and computer at the same time to one pair of headphones?

[Turtlebeach]

my headset uses optical s/pdif cables to connect to devices. have a digital audio splitter, when i plug both the cables from my xbox and computer to the splitter, I can hear audio from my xbox but not from my computer, but when i unplug the cable from my xbox i can hear audio from my computer. How do I fix this? how can i get audio from both my xbox and my computer at the same time?

 

[americanaudiophile]

The splitter is meant to send one source output to two inputs not mix two inputs to one output,
Since it sounds like all your connections are digital I don't think you can do it. With analog connections you would use a stereo mixer - headphone amplifier.