Audio cables from DVD to mobo

I am an inexperienced builder, but am trying to assemble a new system. I have a LITEON LH-20A1H DVD and an ASUS p5Q Pro mobo. The DVD has output pins for both analog and digital audio (as well as the standard 40-pin data output).
I do not have a separate sound card (just using the mobo sound) and the mobo has a connector for analog audio cable, but I do not see one for digital audio.
However, I am wondering if I even need to connect the separate analog audio cable? Doesn’t the sound also go through the 40-pin data cable at this point?

You don’t need an audio cable attached to the dvd drive. Haven’t used one in years.