Help needed with optical digital audio output on iMac

[baseman007]

Hi,

I am using an iMac connected with a Toslink and an optical cable connected to my audio receiver. Everything worked at first with the volume locking, when the Toslink was inserted. The optical cable still works and I tried changing the Toslink, but I am getting no sound output or any red light. The volume has also stopped locking, when I insert the cable. I am also not getting any option for digital output under Sound in System Preferences or in Audio MIDI Setup in Utilities under Applications.
Please help me. Any help would be greatly appreciated.

Thanks in advance from baseman007

[baseman007]

Please help me. I would also like to add that my analog audio output still works.

Thanks in advance from baseman007