What codec are you using to listen to the music? If it's G729 then it will sound bad. It's designed for voice and music does not encode well with it.
If your server is set for G711, and you are listening via a G711 connection, then check that you have used the correct encoding type as well (CCITT u-law http://snafder.blogspot.co.uk/2011/01/saving-wav-files-in-ccitt-u-law-format.html)
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