Probably not a whole lot in the sound quality compartment, if anything.
Now the audigy 2 zs can technically get higher sound resolution then the Santa Cruz, but in pratice your probably not going to notice anything.
Better off getting a reciever that can decode sound digitally. That way you can move the analog loop out of the computer were all that electromagnitism bounces around and move it to external box via SPDIF. That will end up making a bigger difference, probably.
But if it's just for gaming, then your probably going to see a improvement by switching to the Audigy 2 ZS.