Digital Out Connection

Has anybody used this output successfully? I bought a new digital cable yesterday but I'm not getting any signal in my audio card (PreSonus Firebox.) Same story with my keyboard, no signal.

I have selected the proper input signal in my software mixer application by the way so I don't think it's that.

I am trying to narrow down the possibilities and it just may be a faulty cable but I wanted to know if I'm supposed to change a setting somewhere in order to get the digital signal out. The manual states the digital output is the same as the main stereo out. I know you have to change the setting from ANALOG to DIGITAL when you want to *record in* but there's nothing about *recording out.*

Any clue anybody?

I got my answer straight from PreSonus. I need to change my clock to digital in the control panel application that came with the audio card. In case someone else encounters the same problem.