6.3 Adding Audio Capabilities with a Sound Card
6.3.5 Connecting the CD-ROM or DVD player to the sound card for digital audio
After installing the sound card, the next step is connecting any internal components and cables to the sound card. A common connection is cabling the CD-ROM or DVDROM drive to the sound card to produce digital audio. All CD-ROM drives have an analog audio out connector for connecting to a sound card. This four-wire connection uses the CD-ROM's D/A (digital to analog) converter to pass two-channel analog audio to the sound card for output through connected speakers. These connectors are labeled as analog audio out and keyed on both the CD-ROM and sound card to ensure the correct type of connection.

Most DVDROM drives (as well as some newer CD-ROM drives) offer a digital audio out connection. DVDs are capable of audio streams containing multiple channels. A multispeaker sound card can separate these channels and output them using the correct speakers to create a surround-sound environment. The two-wire digital audio connectors are labeled and keyed on both the drive and sound card to ensure proper connection. After making one or more connections between the sound card and a drive, it is usually required to configure the connection using the sound card setup application.