Cross DJ audio setup problems

Hi. I have a PC with a Realktek audio soundcard, running Windows 7. On the back of my computer, I have an audio jack for up to a 7.1 surround sound: front speaker jack, side speaker jack, subwoofer jack, rear speaker jack.
For the Cross DJ application, I was thinking I could use the Dual Stereo routing option so that I can designate my front speakers for live music and the rear speakers for the cue. But for some reason, I can't select 'LEFT/RIGHT' for both output 1 and output 2. When I set that to one output then try to set that on the other output, the other selection goes away and gets set back to 'NONE'.
Do I need another soundcard or should I just go with a split mono routing option. If I do the split mono routing option, I'm wondering if there are speakers that have independent controls.
Any suggestions or tips will be greatly appreciated. Thanks!
For the Cross DJ application, I was thinking I could use the Dual Stereo routing option so that I can designate my front speakers for live music and the rear speakers for the cue. But for some reason, I can't select 'LEFT/RIGHT' for both output 1 and output 2. When I set that to one output then try to set that on the other output, the other selection goes away and gets set back to 'NONE'.
Do I need another soundcard or should I just go with a split mono routing option. If I do the split mono routing option, I'm wondering if there are speakers that have independent controls.
Any suggestions or tips will be greatly appreciated. Thanks!