What do you expect to find? 256 kbps will almost certainly sound noticeably better than 32 kbps.
If one just wants to compare master quality, then import the CD at 256 kbps AAC VBR (i.e., iTunes Plus setting). Comparing different masters at different bit rates doesn't give us much useful information.
Ooops . . typo. I meant 320kbps
Okay. That still leaves the question about what information you are trying to obtain. You have two variables (bit rate and master) and only one comparison. You would need to either use the same bit rate (256 kbps AAC VBR) or files originating from the same master.