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. "We didn't do anything else to it," he said. More →