First of all, were the tracks mixed down to stereo before you gave them to your guy to master? If not, maybe the problem is in the mix. Excessive use of compression and limiting during the mastering process on stereo tracks can also have the effect you describe. Also, overuse of high tech magic boxes like "finalizers" can have the same effect. Rather than just lowering the overall level, it would be better to backtrack and find the nature of the problem. You do have the raw, unedited tracks archived, right? Go back and listen to them. If the vocals sound better there, then find out where in the process they became too lound. Good luck, Al