Render your tracks down to WAv...then compress the WAV to an APE file which makes file smaller.
Tricia posted the link to Monkeys Audio (APE)
Downlod monkeys Audio
open up the program and choose compress in top left.
Then just open up the files you want to compress and drag and drop right into monkeys audio and click compress button.
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When receiving APE files just change to uncompress top left menu and uncompress.