I have two surround sound systems, how can I hook them into my computer to play at the same time. One is 5.1 and one is 7.1, atm one is plugged in via optical link and one is through and audio jack into the headphone port.
Any help is appreciated thanks.

i use this http://www.officedepot.com/a/products/200742/Belkin-RockStar-Audio-Adapter/?cm_mmc=Mercent-_-Google-_-Networking_and_Cables-_-200742&mr:trackingCode=7B2AB722-411F-E011-AD27-0019B9C043EB&mr:referralID=NA