The iTunes Plus AAC M4A format, introduced by Apple Inc. in 2007, represented a significant shift in commercial digital music distribution. This paper examines the technical architecture of the iTunes Plus format—specifically the Advanced Audio Coding (AAC) codec encapsulated in the MPEG-4 Part 14 (M4A) container, encoded at 256 kbps variable bit rate (VBR). We analyze its perceptual audio quality relative to MP3 and lossless formats, its role in eliminating digital rights management (DRM), and its historical influence on industry standards for downloadable music. Findings indicate that iTunes Plus AAC achieves transparency for most listeners, offering superior efficiency to MP3 at equivalent bitrates, and paved the way for modern streaming-download hybrid ecosystems.