To be honest with you, it sounds normal to me. I don't hear anything out of the ordinary when I compare it to my car, or any other turbo Subaru engine I've heard. These engines are incredibly loud, especially in the cold.
Subaru (and almost any other dealer service department) has a tech line that they can call to get the breakdown of logical steps to troubleshoot issues. Just because they are mechanics and service techs, doesn't mean they are going to know all the issues all the time.