**MP3
source files are not recommended in mastering. The filtering
involved removes much of the detail mastering enhances, and
never sounds as good as it should. If you're using dial up and
cannot upload large files, then try a higher resolution MP3
such as 320kbps or variable bit rate, or cut the wave file in
half so it's not so big. That way you get a better idea as to
what to expect.**