Asus Xonar DGX to denon avr-590

[Thenearfuture]

Hello, I just bought an "Asus Xonar DGX" with 3.5mm mini jacks but my 5.1 receiver only takes rca and hdmi. How do I get the required output of 5.1?

 

[americanaudiophile]

DGX seems to have an optical audio output. The receiver has optical input.

 

[Thenearfuture]

DGX seems to have an optical audio output. The receiver has optical input.

Ya but isn't optical only 2.1