Bobby Owsinski got some Mastered for iTunes questions answered directly from Apple representatives.
“Mastered for iTunes” is only an indication that a hi-res master was supplied; it’s not a separate product. There will always be only one version of the song on iTunes at the same price as before. “Mastered for iTunes” doesn’t mean you get to charge more, or that iTunes charges you more. Everything is like it was before, you just supply a hi-res master so it sounds better.
Which would indicate that anybody using iTunes Match is getting the Mastered For iTunes version of tracks. Good news if you thought you’d have to repurchase all those Pink Floyd albums for the Mastered for iTunes magic.
Also on sound quality:
Speaking of the sound quality, iTunes is now using a completely new AAC encoder with a brand new algorithm and the sound quality it produces is stunning. It provides an excellent encode if you use a few common sense guidelines (more on this in a bit), and if you do, the result is almost impossible to hear (at least on the music we listened to). I mean, there we were, mastering engineers Eddy Schreyer, Gene Grimaldi plus myself, listening in this fantastic listening environment, and we literally couldn’t tell between the source and the encode most of the time.
Mastering engineers, people who do this professionally for a living, have trouble identifying a 24/96 studio master from a 16/44 AAC file. Meanwhile, read any of the comments on these types of articles and you’ll find comments from people who think they have golden ears and demand FLAC, high-resolution downloads.
Why? Because higher numbers are better. It’s science!
They did the math, but they didn’t use their ears.