Does your DVD player have analog outputs? If so, route those to an input on the back of your Yamaha and assign the zone 2 to use that as the source. I'm doing something similar with my Squeezebox. I run an optical cable from the Squeezebox to one input source on my receiver for main listening and use analog cables to a separate input for zone 2 listening. In my case, I use the CD inputs to route my Squeezebox analogs to since I don't have a CD player.
If your XM source is separate and has both digital and analog outputs, you could do something similar. It would depend on how many open inputs you have on the back of the Yamaha. I don't have XM, so I'm not sure how this integrates with your receiver.
