Wow. Kinda surprised by the difference. I can't be absolutely sure it's not a placebo effect but the stereo separation does seem much better than my Audigy 2. When I played mp3s on my Audigy, I used a Winamp plugin called DFX to make them sound better (it cheats since it's a sound shaper). The X-Fi without any plugins, since I'm using the included Media Source, sound about the same as the DFX enhancements, maybe even a little better since it's not as muddy, seems cleaner, crisper.
Shame I jacked up the Line-In. Oh well, I purposely started on that opamp because I knew I would likely never use it and it was a practice run. If I need to run a mic though, I'll have to use the onboard audio.