Charles,
AIF (AIFF) and WAV will give you 100% reproduction of what is on the CD. All the others are compressed to save space. But Apple Lossless (ALAC) does a real time uncompression and very little is lost if any, as it is Lossless. While MP3 is a lossless compression format and throws away bits and while best for saving space and streaming it is not ideal for playback if you have the space. AAC Encoder is usually perceived better sound quality than MP3 (high bitrate version) comparing lossy compressed formats, but usually only iTunes can playback this format so it is not a universal format.
The cool thing is that you can compare yourself on your system with just one song.....
In itunes. first import a CD in AIF format (also check the Use Error Correction option)
after that is complete, then change the the import Setting (go to iTunes > Preferences > General Import Settings and choose another quality (eg MP3 128kbps)
You do not have to re-import the CD--just highlight a song you know very well, press Control and mouse click (or right click on a three button mouse) that song to get a pop up menu and you will see "Create MP3 Version", this creates a converted copy. You can then rename that new version adding a reminder to the song name (click on the name in itunes). From there, you can then repeat this process with a couple other format options. you need to start with the AIF or WAV version though. then listen to each.
WAV is also 100% copy but on a Mac you loose artwork tagging capabilities and maybe some other tagging feature, but the data of a WAV and AIF should be identical. I am sure there are tests out there that prove that .001 % is changed in one of the versions but you get the point.
I use AIF myself. That said, some songs sound very good in ALAC and even high bit rate MP3, it depends on the song, recording, and playback equipment.
I hope that helps a little. I am sure some experts will chime in with hard sampling rate facts, etc.
have fun.
cheers,
ed
