Backup SACD with iTunes or Disk Utility?

cdda2wav will import discs such as HDCD, but the result will be standard PCM audio in the form of a WAV file, i.e. 16-bit. Some of these other special disc formats cannot be ripped at all, and some can, but only with illegal software, and there wouldn't be much point to doing this, since you still couldn't burn a similar disc, but only play the files back on a system with a very high end sound card and software supporting audio of that quality.

In any case, this issue has gone way beyond the scope of iTunes, since iTunes has nothing to do with any of this.

Dragging an AIFF "file" from a mounted audio CD to a location on your hard drive is not technically ripping a CD, and definitely not the best way to get a clean copy. To start with, there actually are no "files" on an audio CD, rather uncompressed, raw PCM audio indexed with a table of contents. For the sake of convenience, operating systems such as OS X "see" the audio tracks as "files."

To ensure perfect rips on a Mac, the best software without question is Max (with full paranoia enabled, and skipping never allowed). Still, the best you can do is CD quality audio, even if the original disc has higher quality audio, and assuming your CD drive can even read the disc in question.

To repeat some of the main ideas in this thread, Disk Utility is not capable of copying audio CDs, video DVDs, etc. It is a utility for copying different types of data discs, among other things. iTunes simply doesn't offer playback support for files of the quality you're dealing with.

As much as most people on these boards don't like Microsoft products, it would seem that they certainly were an early entrant to the market with playback and encoding support for multi-channel, high resolution audio. Windows Media Player for Windows can play a lot of this stuff, but ripping certain kinds of discs is still difficult, and sometimes impossible, on Windows PCs.

I would like to help more, but in the case of esoteric audio disc formats and what you can do with them, your best source of reference may be Hydrogen Audio.