"320kbps" refers to the highest bitrate for MP3 files. In an era where 128kbps was the norm due to limited storage and slow dial-up/DSL speeds, 320kbps represented the "Gold Standard"—the closest a listener could get to CD quality without the massive file size of lossless formats like FLAC [4, 5]. The Source: "IB" likely refers to Invision Board
Some notable singles: