Audio mastering is one of the most misunderstood and often overlooked steps in the recording process. After all the mixing is completed, there is still one last step before the replication process - CD Mastering. The mastering engineer has the job of listening to all the songs that make up an entire project and determining what needs to be done to give the CD a smooth, seamless flow from the first song to the last. This usually involves EQ adjustments, level adjustments, and spacing between the tracks. The mastering engineer also brings a "fresh" perspective to the project, helping ensure that everything is the "best it can be".
I prefer to use an analog mastering path because of the "musical character" of the individual components. It's a subtle character, but it's there - to me, digital has no character and I believe music is about soul and feel and emotion. I have digital tools available when needed, but my "go-to" gear will always be analog.
A very popular option these days is "analog layback mastering". Being that most projects are recorded in the digital domain, this method of recording your project to analog tape can help get rid of some of the "digititus" associated with projects done completely in the box. I'll record your masters to tape on my 1977 MCI 2 track mastering deck with transformer balanced ins and outs. Analog tape smooths out the top end and tends to give a nice little "bump" on the bottom around 60hz, and it adds that real tape saturation. Honestly, I have yet to find a plug-in or a box that does this the way real analog tape does.
My main goal in mastering is to help the artist fulfill their vision and sonic goals for the project. It's more than turning knobs or raising levels - it's about listening to someone's "heart and soul" and being able to help them take that to the next level.
"Mastering is the process of turning a collection of songs into a record by making them sound like they belong together..." The Mastering Engineer's Handbook, Bobby Owsinski