What would the quality difference be between 2 files encoded at 96kbps, mp3 or aac from these 2 sources?

-.wav file
-.mp3 already encoded at 320kbps

Reason is I have some mp3's I downloaded from the net and they are at a high bitrate but wanted to convert them to a rate of 96kbps for my ipod shuffle(limited space), to either mp3 or aac, which ever is better, I would of course keep the original files in archive...


Thanks!

the majority rule is that the files encoded from WAV as source will sound better. A 320kbps MP3 file as source you bear in mind that that is only 30% of data from the original WAV file, so the quality from re-encoding will be worse.

But as you stated, it's a "very high bitrate" 320... and if it's done with a good MP3 encoder such as LAME-latest, I don't think you should hear a difference, but only yourself call tell that.