When you do a reinstall your /home should remain untouched, assuming you have a separate /home, so if your mp3's are in /home then you will not lose them. You should still make at least one backup of these files to another device, flash memory, external hdd, dvd-r, but I would make 2 backups to be on the safe side.
Yep I do just the same, I've had a files back up corrupted some years ago and I became very paranoid