Also in the digital world there is Data Compression to watch out for. I'm not sure of your mixdown process but if your sending it out to a stereo WAV you should be safe, but if you are going to MP3, check the resolution/data compression. For the Internet you want at least 128k before it starts sounding really noticibly bad. The higher the res the better the sound.

Also, make sure you do EVERYTHING as a WAV file, all the way to mixdown. Once you have a WAV of the mixdown, then you can create or convert to MP3 for pasing around the Internet and stuff. But, just make sure your orignal is in WAV.

If you master it, make sure you are mastering the WAV mixdown. THen convert the Mastered WAV to MP3 if needed.