Assuming you do get the Chaintech, the best thing would be to leave the Audigy 2 in, add the Chaintech, and experiment for a little while. The worst probable scenario would be that some computer conflicts with two sound cards force you to uninstall them and reinstall the new one, which isn't that big of a deal. If both cards work together on your system, then you can compare them on various games (and music, for that matter) and draw your own conclusions.
In theory, the A2 is a better gaming card and the Chaintech should be better for music. But if you are going to have both cards in your hands anyway, it's best to try for yourself and see what will be best for you in practice.
Edit: And then, you will have firsthand comparisons to pass on to the next person who asks about Chaintech vs. Audigy