mp3 discs are simply data discs with mp3s on them. To create one in Nero 7, create a new CD compilation (make sure the dropdown box says CD and the icons are silver, not gold). <BR>Choose CD-ROM(ISO).

If some differences are too small to be determined by a blind A/B test, how small is too small? And who decides?

I've used EAC to do this. Instead of ripping individual tracks, tell it you want to "Copy Image & CUE Sheet." That will make a single WAV file of the entire CD, then you can convert to MP3 from that.