Not sure if you have stumbled across this link or not, but it's an interesting study done by European broadcasters (the pretty graphs start on page 21!):
http://tech.ebu.ch/webdav/site/tech/...h/tech3324.pdf
For those too lazy to click the link, basically the "Original ANC", "DTS 1500" and "DD+ 448" (AC3 640kbps) tracks all score 92-95% on the perceived quality score (so the lossless formats should score the same as "ANC_Original"!) ...
7ek