I've heard numerous recordings done by people in their home studios, and yeah, they've sounded ok, but then they've sent them to get them professionally mastered, and the finished product is a world of difference. Here's what I currently believe "mastering" is consisted of: 1. The person mastering is a new set of fresh ears. 2. The person mastering is in a very acoustically treated room with good monitors. 3. Mastering is just a process of limiting, compression, and plain old EQing. 4. They're probably just more experienced then you at mixing. .....I'm not too sure.