Hello fellow Line 6 enthusiasts!

I recently purchased a Line 6 Pod HD 500 -- and while the phone out connection has served me well, I find myself wanting to get a better signal in form of the digital S/PDIF out available on the device.

Right to it:

I bought a RCA to 3.5 MM cable, thinking this was all I needed to go from the S/PDIF on the HD 500 to my computer's sound card (the "line in" input), but all I get is a very quiet humming. Now, I should point out -- it is NOT the same humming as from a ground loop -- it just sounds like static.

Could someone point me in the right direction here? What do I need to do to connect the HD 500 to a computer sound card through the S/PDIF output?

Many thanks,

WZD