John said it rather well.

I've been mastering professionally for over 15 years and that is still in a nutshell what I'm doing. It's like having an editor proofread a book before you release it. Sometimes they catch things that are extremely important (words in the wrong spot can change the entire meaning of the sentence) and sometimes they make suggestions on how to better get across the emotion or feeling you're trying to convey. Overall, they didn't write the story and make up the characters but their influence can make the experience of reading the book much more enjoyable without the reader ever knowing what the editor/proofreader did.... As mastering guys, we are able to easily get the 30,000 foot view of the project and get closer from there.

As far as the tools you can use... can't help you too much on specifics as to what being done on the "prosumer" level or whatever since I've been using the "pro" stuff for years but I just wanted to convey the importance of not taking the mastering stage too lightly. I don't think you can use just any eq or compressor. I think you need something that you know sounds good. Any eq can make a dull track brighter but does it also bring up a bunch of other high frequency crap that an EQ with a more adujustable cue would allow you to get the same brightness without the crap.... Especially in the digital realm. You can get some pretty crunchy and non-forgiving plugs.... I'm not a big fan of plugs but I've heard good things about the iZotope. I do most of my processing with outboard boxes.

So there's my 2 cents. Hope it helps a little.

Paul

Paul Elliott
Head Mastering Engineer
The Soundlab @ Disc Makers