So, what is “mixing”, and how does it happen?
In sound recording and reproduction, audio mixing (or “mix down”) is the process which commences after all tracks are recorded and edited as individual parts. The mixing-process can consist of various processes but are not limited to setting levels, setting equalization, using stereo panning, and the addition of effects. The way the song is mixed has as much impact on the way it sounds as each of the individual parts that have been recorded. Dramatic impacts on how the song affects the listeners can be created by minor adjustments in the relationship among the various instruments within the song
What does that mean for your song? It means that the rough mix you had put together may sound good, but is it really the best the song can be? Does it take full advantage of the stereo field? Are your rock guitars big and loud, with drums that hit hard? Is there a good sense of space and breath on your quieter songs? All of these things and more can go into taking a song from sounding “good” to “great”.
This is where the professional mix engineer comes in. While you have spent hours improving your musical chops so you’re the best ancient Mayan astro-pickle player around, I have spent those same hours making sure that when you record yourself, the final result sounds even better than it did in your head.