I use Linux, so I can't comment from personal experience, but
this site has a video that should let you use Garage Band if you wish. You can also use iTunes, if you don't mind re-ripping the CDs, and this would allow you to join the tracks with no loss of quality. Make sure the tracks on the CD are showing up in track order, select any number of consecutive tracks, and in the Advanced menu choose "Join CD tracks." (Apple has a [very short] article on this
here.)
For Windows or Linux, I'd recommend using Exact Audio Copy as explained
here. Exact Audio Copy is widely recognized among audiophiles as the best way to get completely flawless rips. For more info, see
this guide. (It's only a Windows program, but it apparently
runs fine on Linux too under
Wine.) It's what I prefer to use. Edit: I tried it under Wine, and it doesn't exactly work. So this may not be an option for Linux users--or at least not without some tweaking (which I'll try). I may have a use for my Windows partition after all.
I ran across another interesting method that should work if (a) the files use the same encoding (which is almost definitely the case if you ripped them all at the same time), and (b) you're not afraid of the command line. And it doesn't degrade the sound quality as well, and is very fast. As an additional bonus, it should work on Windows, Mac, or Linux. First make a copy of your music somewhere else, to keep it safe. Then open a terminal and use
ID3Cleanup (with the
-remove tag) to remove all ID3 data from your files. Then, if you're on Linux or Mac, use the command
cat track1.mp3 track2.mp3 track3.mp3 > compilation.mp3 (where track1.mp3, track2.mp3, cat3.mp3, etc. are the source files, and compilation.mp3 is the joined version.) Voilà ! They're now joined. (If you're using Windows, make sure you have only the files you want to be joined into a single MP3, and then use
copy /b *.mp3 compilation.mp3.) I just did a quick test, and it worked fine for me. Thanks to
this page for the tips.
I apologize for assuming that the original questioner(s) used Windows. Although that's about 90% likely, I myself fall into that other 10%, and I should have thought of the others who do too.