Dolby Digital & DTS question

…I don’t understand about Dolby Digital & DTS. My surround sound amp supports both and the WDTV can have one or the other or both selected.

Should I select both or just the one (if so which), or does it not matter?

Thanks.

Up to you what codec sounds better for you personal sensation. Dolby Digital and DTS support both multi-channel audio.

Dolby Digital: https://en.wikipedia.org/wiki/Dolby_Digital
DTS: https://en.wikipedia.org/wiki/DTS_(sound_system)