Hey, I had the same problem when I first bought my Ipod. The issue is not with the Ipod its with iTunes, go to Preferences then Playback, change the volume on SOUND ENHANCER, I recommend the sound check but thats personal.
After you do that, connect your Ipod and go to settings uncheck maximum volume, and sync. I added memory for Ipod usage to make sure (decreases # of songs for ipod usage)
Good luck I hope this solves your problem it solved mine.