iTunes Match
When signing up and using iTunes Match, are my original music files altered in anyway?
When signing up and using iTunes Match, are my original music files altered in anyway?
The original files on your computer are not altered.
However, the matched versions may differ from the originals. Files that match will be the iTunes Store copies, which are in AAC/256 format. Files that do not match may be transcoded to 256 in certain cases.
iTunes Match