which way of saving beat is better?

resample from main out to mpc's memory or record to line in of soundcard? I mean, is there difference in quality?

by the way, sorry 4 my english

going through your soundcard depends on the quality of the soundcard's analogue-to-digital converters. if you don't have an good soundcard, it might be bad.

I think your best bet is keeping it in the mpc, doesnt sound like u have a great soundcard. This will also keep things simpler cutting your computer out of the equation, unless you need to bring it into software for mixing, editing, etc..