You could spend $1000 having Bob Katz master your CD, or you could save a few bucks, like Ry Cooder did, and simply entrust the job to iTunes:
Then Mr. Cooder noticed something else: When he burned a copy of the album using Apple’s iTunes software, it sounded fine. He didn’t know why until one of his younger engineers told him that the default settings on iTunes apply a “sound enhancer.” (It’s in the preferences menu, under “playback.”) Usually, that feature sweetens the sound of digital music files, but Mr. Cooder so liked its effect on his studio recordings that he used it to master — that is, make the final sound mixes — his album.
As the article states, Cooder is likely the first well-known artist to master an album through iTunes. But the effect of iTunes’ sound enhancer is obvious to anyone who hears it. So does the software do anything that might qualify as mastering? Here’s a collection of thoughts on how iTunes ‘sound enhancer’ functions:
What iTunes does in this respect is the same as the ‘Wide’ button found on ghetto blasters in days of yore – some high frequencies from each channel are phase-inverted and fed to the opposite channel. This makes the stereo-width apparently greater – but comes at the expense of any real definition of placement.
(And for the record, I’m not endorsing the use of iTunes software in place of a trained mastering engineer. Your music should mean more to you than that.)