On a side note, if you truly want to test your systems capability, you can download truly high-res studio masters in FLAC format from Linn Records and then convert them to Apple Lossless with a bit transparent converter called Max so that they will play in iTunes. The music selection is small, but the quality of the files are equal to that of a SACD.
http://www.linnrecords.com/
http://www.linnrecords.com/