Also,
Different burners will definitely record at different levels. I have a super drive in my Mac and have songs in itunes that frankly sound like crap compared to burns I have done on my outboard Plextor drive, substantially louder, cleaner, better. Frankly I do not burn on the super drive anymore when doing a master copy. And yes itunes basically will make your mixes sound dead and boring. Don't even bother with it. I am similrly unimpressed with the drive Mac used on the G5's it some sort of Hitachi and not a very good drive either.