OP's already made his choice, but just leaving this for future readers.
You will not want to use any Creative cards for "Audiophile" needs. Creative's focus since quite some years seem to be on the Gaming market, especially with their X-FI series. They've gone all-out into EAX and CMSS 3-D technology, while basically ignoring the humble 2 channel stereo.
On the Creative platform, you'd be better off with Auzentech soundcards, which use the same chipsets from Creative, but are engineered more towards music reproduction.
Asus had really shaken up the lower end of the PC "Audiophile" market with their Xonar soundcards. The DX/D2X had been compared in reviews to the best of the Auzentech, and found better. The Xonar specs too are impressive, with superb SNR ratios. The Xonar DX is a lot of bang for the buck at its cost.
The only drawback to the Xonar DX are the Asus drivers. There are many minor niggling annoyances that can add up to give you a big irritation. For eg, when you use Front Panel Headphones, the drivers will not automatically route the audio. You have to manually select "FP Headphones" in the Asus Control Panel. Another issue I've seen is that the implementation of the software feature "SVN" (Smart Volume Normalization) creates popping sounds when turned on. Its best to turn it off (SVN in itself is a corruptor of audio, by reducing Dynamic Range).
Do note that Creative haven't fared much better than Asus in the drivers dept. When Vista came out, they basically refused to put out updated drivers for older hardware in order to force ppl to go for newer hardware with proper driver support.
Reviews of Xonar DX (Including one by our own Cranky, on TE) :
http://techreport.com/articles.x/14500
http://www.bit-tech.net/hardware/2008/05/26/asus-xonar-dx-pci-express-soundcard/1
http://www.techenclave.com/reviews-and-previews/asus-xonar-dx-review-125339.html
http://www.extremetech.com/article2/0,2845,2282513,00.asp
Disclaimer:
I have a Xonar DX in my system, and I've never actually heard an X-FI card.