I've recently begun downloading files in Lame MP3 format, but still playing them on my iPod.

As you may know, you can designate an equalization setting (Rock, Pop, Loudness, etc.) for songs in your iTunes library; if you turn the EQ Setting on your iPod to "off", whatever setting you designate in the iTunes library will be used by the iPod when you play the file and listen to the music.

Although one can designate an EQ setting for an MP3 file in the iTunes library, it doesn't seem to make any difference as to the sonic output. Similarly, when playing an MP3 file on my iPod, I can change the EQ setting manually, but there doesn't seem to be any change in the sound.

Is there something in the AAC codec that allows for use of the EQ that is missing in MP3?

The EQ setting in iTunes works for any file it can play, including MP3. Just to confirm, I just tried it on both Windows (iTunes 7.6.2.9) and an older iPod nano. So, it works for me... even though I never use EQ settings.

Thanks. I think I found the problem and have it resolved.