Re-ripping music collection to new iMac

My hardcopy CDs are, in most cases, copies themselves that I burned from public libraries, friends CDs, etc.

You do realize that this is a blatant copyright infringement? Not sure why you'd want to share that information publicly.

As far as whether to re-rip; It depends what resolution you ripped them at in the first place, and how discriminating you are about the differences in formats. You do not want rez-up a file, so if you ripped them at low-rez and you want high-rez then re-rip the files from the originals. If you want quality audio you should choose a lossless format such as Apple Lossless right from the start. If the files were ripped in low-rez you will gain no additional quality by converting them to a higher rez format IMHO and you may even introduce some distortions. I don't know the Nero Burn sofware, but if the CD's are indeed direct copies of the original CD's then you can re-rip from the copies. If Nero Burn compresses the files, then you will have to rip from the originals to get the best quality. I don't think EAC is compatible with Mac - at least, last time I checked there was no Mac version of that software (PC only). I'm not sure if EAC files are cross platform(?).

Thanks for the input so far. It is sounding to me like it would be a waste of time to re-rip. The new iMac and Cavalry 2TB HD unit are both on the way so I'll follow the advice and just load it up - try out a couple of re-rips and compare. The CDs were ripped originally in a WAV format (not compressed) so there probably wouldn't be any advantage to re-ripping. You have confirmed my suspicions.

FLAC.....google it!
Winamp handles it natively...and it makes files about 45% reduced from the WAV and can be turned back into a bit-perfect copy.

What I do is rip the CD into WAV (uncompressed original file) then convert it to FLAC using EAC. I keep both files. I then have the original WAV that I can always convert into any other compressed (lossy) file I made need. I ripped my 750 CD's 3 times before I decided to keep a WAV copy. Terabyte USB2.0 or 1394 drives are cheap enough today to do this, as well as have a backup of all files.

Tubejack: Sounds like you are using a PC. I will be using a Mac and have been advised that EAC is not available on Mac but haven't checked that out personally. I do use EAC now for ripping into the old PC (WAV) and am happy with the way it performs. I'm just hoping that the Mac salesman will be able to upload the library into the new Cavlary 2 TB HD and hence into the Mac. I presume that the library would then be in an AAIF Mac file (non-compressed). If you ripped your CDs three times, you have made some good comparisons!!