D-Link DSM-750 - MediaLounge High-Definition Draft N Media Player User Manual page 19

Section  - Configuration
Connect a coaxial digital audio connector into the COAX connector on
the DSM-750 and the matching opposite end of the cable to the audio
input of your audio system.
Note: This cable is not supplied.
D-Link DSM-750 User Manual
Coaxial Digital Audio
1