After being uploading to the iTunes Match I did a test to see how my unmatched Apple lossless files would download to my iPhone . I downloaded a song that was 40MB in size on my laptop. After a very short download, the free space on my iPhone only decreased by 10MB. I think that's good evidence that a big lossless file on your laptop will come back to your iPhone as a 256.<br />
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Or maybe iTunes makes a re-encoded copy to shorten the upload and reduce storage on their servers. That would be my guess.