Add a sub to this system?

[Matt34]

Alienware 14x--USB-->Behringer U-Control UCA202 ---RCA to XLR---> KRK Rokit 6 powered monitors

Partsexpress has the Sub1200 for $99 so if I want to add it to my current setup, what are my options?

 

[Matt34]

Meh, don't think it's worth the hassle since the sub doesn't have rca outputs. I should just get the matching sub that has all the connections I need.