Who says you can't?
8) Why its not recommended?
Well re-encoding will lose you some quality but if you want to, you CAN! And better yet with a very nice, feature full and FREE tool.
http://www.dbpoweramp.com/dmc.htm
That is it.. Look no further
. Convert from ANY format to ANY format. Batch conversion - no problem. Additional plugins - you have got them.
Enjoy yourself!
