By stand alones you mean mixer preamps or stand alone preamps? If you're talking about stand alone preamps of course if you had like an expensive preamp going it'd be better than the ones on the card, but the thing is you can always buy a good preamp and run the mic to that then the preamp to the card. However, even the preamp on the card sounds good. I recorded an opera singer not too long ago with my AKG D-790 (which isn't that good of a mic) and ran that directly to the direct pro. Even that sounded pretty good. The card itself comes with its own little "virtual mixer" where it has compression, eq, etc. for each input. It even has some effects such as reverb.
What I was doing with it was running everything to my mixer, then i'd run the outs of my mixer to the sound card (only because I needed more inputs recorded at the same time). If you're recording vocals or guitar this thing is great. I've made a lot of good demos with it. The only reason I'm getting rid of it is because I needed more inputs to record simultaneously.
