I finally upgraded my aging Sound Blaster Audigy 1 to an Asus Xonar DX card last night. It's the first time I've had a sound card that requires an additional power source (floppy connector) like current video cards do. I have a pair of
Audioengine A5+'s already so it's matched with a very capable set of speakers.
So far I'm not crazy impressed though. The bass seems more powerful and present than it did before, but the clarity doesn't seem *that* much better. It is better, don't get me wrong, but it's fairly minor from what I've heard so far.
Anyway, just thought I would share my personal experience. I haven't used on-board sound for a long time now, so it may have gotten much better, but the last time I tried it out compared to a sound card (Sound Blaster Live! 5.1) it was practically a night and day difference.