Yeah the xonar has an optical spdif. You will need the following cable.
http://www.ebay.co.uk/itm/like/162087113093?lpid=122&chn=ps&googleloc=9046620&poi=&campaignid=620865095&device=c&adgroupid=27378760866&rlsatarget=pla-181484323026&adtype=pla&crdt=0
A decent AV receiver will set you back a...