You need to use an optical cable to run the surround sound from the Xbox 360 to the receiver.
There's a port on the A/V cable connector that connects into the Xbox 360, the run that into an optical input on the receiver.
Be sure to change the hardware settings in the Sound section to Dolby.
There's a port on the A/V cable connector that connects into the Xbox 360, the run that into an optical input on the receiver.
Be sure to change the hardware settings in the Sound section to Dolby.