HI, I just found this site with unlimited free online mastering.
I tried it and it sounds ok for me. Maybe you want to try it too?
You can make an account and publish your songs and even let other people collaborate.
I didn't find the right solution from the Internet.
References:
http://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=415986#Post415986
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