Programming an XR11 remote for the audio output of an XG2V2-S box

I have an XR11 paired to my XG2V-S box. I want to listen to my audio directly from the red&white audio output of the XG2 box itself, rather than from my connected monitor or sound system. It works fine, except that I can't control the volume/mute from my remote. Is there a remote programming code for the XG2 box audio output itself? (Since it's a Samsung box, I tried all the likely Samsung codes but none of them work.)