I did look at DACs a few years ago. I'm assuming you can't use the same sort of software, that you get with cards, which means the cards still have the edge. I'm not sure about that Pob, does the software enhance or not, the sound. I prefer the surround and enhanced sound even for music. To be honest once a system is working, I tend not to think about the components.
I don't think many people realise just how much our minds filter and edit, both what we see visually, but what we hear.