And, of course, you could use standalone MP3gain if you would also like to normalise existing MP3 files (rather than transcodes, as handled by caudec).
"caudec -G album *.mp3" will apply album gain (use 'track' if you want track gain) to your MP3 files, using mp3gain. It will work everywhere, but I don't know if you want that. No soundcheck required, and it will prevent the iPod's EQ presets from clipping.
I assume sox is not involved in this command?