I get a good sounding mix for a kick drum or bass that has depth and punch, but then I export it as a track and it plays back terribly, like it overdrives and sounds like a big "pfuh" rattling. This is with different mixing consoles and software as well; it sounds great in the software, then comes out terribly in the mixdown. Why is the software able to play these bass frequencies cleanly and iTunes/Quicktime/etc. not? It obviously has nothing to do with the speakers. I can never get my best mix and have to turn down the punch and depth quite a bit to get a sound that doesn't rattle.