not_heifetz wrote: 1 – Do I need to upgrade my computers integrated soundcard to be able to play/edit music that is already recorded digitally?
2 – Is there a sonic difference between recording to a field recorder and recording to a DAW if the preamps and a/d converters are the same?

1. You shouldn't have a problem with just playing or editing it. HOWEVER you may get better results from a higher quality card for playback quality (S/N, etc.) But as for doing the basics, you can use what's there in a pinch. I have three sound cards in my main system, including the built-in Yamaha sound chipset that's built-in on the motherboard. (I use that for rear-surround speakers when doing surround spot-checking, aux sends, etc.)

2. In theory, no, there should be no difference at all, assuming you're using the same bit depth and sample rate, software, etc. Bits is bits; it's all ones & zero's. (Or actually: ones & NOTHING.)