It's been awhile since I had the old Audigy installed and from what I can find on the Internet Creative's software looks abit different, but where is the equalizer? Sounds to me like you're in need of using it.
I have an Asus Xonar card with original Klipsch Promedia 5.1 speakers and if I set the equalizer to flat across the spectrum (30 to 16k), the sound is obviously very flat, not rich and full. I have a User Defined equalizer setting that I've found sounds very good with most kinds of music.
But yea, if I want to show how poorly the system can sound with this Xonar card, I can set the equalizer to flat. As I remember, I did the same with the Audigy software.