How do I run sound out of 2 sound cards?

Hey guys, so here is my situation. I am trying to learn how to do some really basic DJing, like just fading songs together, nothing hardcore. I have 2 soundcards on my computer, one Soundblaster something or other and another Realtek onboard sound card.

I am using VirtualDJ as my software, and I would just like to know how I can have one output, the Main sound out, to go to my speakers, and the other output, which is the inactive deck at the moment's sound to go to my headphones. Is this possible?
Sorry if I confused anyone.

i dont think you can do that..... well ive never heard of it at least