See my thread. http://forum.audiogon.com/cgi-bin/fr.pl?ddgtl&1230454626&read&keyw&zzeac
I was never able to confirm, audibly or through bit comparing, that EAC does a better job than say, iTunes with error correction. At one point I was convinced that it sounded better, but as soon as I found there was no technical basis for that belief, the placebo effect swung the other way and I heard no difference.
According to at least one expert in USB DACs, EAC's effectiveness is more of a myth than anything. This is because unless the CD is very dirty or damage, you are generally going to end up with bit perfect files regardless of the ripper. Reading the CD is just not that difficult a task for most CD drives.
Some people however, prefer to make sure the following factors are accounted for: 1) cd drive and ripper should use "accurate stream" technology, 2) the CD drive should not buffer audio or if it does, the software should be set to compensate, 3) the CD drive should support C2 error correction.