Originally Posted by
creative.com KnowlegdeBase
The Digital Input jacks found on common home theater receivers are either a Coaxial or Optical Digital Input connectors. These Digital Input connectors are capable of receiving a single data stream only, be it AC3 data stream, DVD, or a regular stereo audio. When the receiver receives a compressed audio data stream such as a AC3 or DVD from the sound card or a setup DVD player, it will decode the compressed audio, and then output to appropriate speakers. These connectors are not capable of sending multichannel audio signals that have been decoded already by the sound card to individual speakers. When the receiver receives such signals, it will output the front channels only, and disregard other channels.
The Digital-Out jack on the Sound Blaster Live! 5.1, Sound Blaster Audigy, and Sound Blaster Audigy 2 cards is a 4-pole mini jack that enables the card to deliver multichannel audio via three discrete streams (Front SPDIF, Rear SPDIF, and Center/Subwoofer SPDIF) to compatible speakers such as the Creative Inspire 5700, DTT3500, or MegaWorks 510.
The Digital Out jack can also send out a compressed, single stream AC3 data to an external decoder such as a receiver.
When a multichannel receiver is connected to the Digital Out jack of a multichannel Sound Blaster card, such as the Sound Blaster Audigy 2 ZS (7.1), the Sound Blaster Audigy 2 (6.1), Sound Blaster Audigy (5.1), Sound Blaster Live! 5.1 or Sound Blaster Extigy, it will only reproduce multichannel audio when playing DVD games, or DVD movies, or standalone AC3 files.
The commonplace multimedia files such as MP3, MID, AVI, WAC, or WMA etc, are of stereo format: right and left only. It is common to hear only front right and front left channels from a multichannel capable receiver when it is connected to the Digital Out jack on a Sound Blaster card. Though there are software applications, for example, the Creative CMSS, that can replicate stereo audio to a surround sound, this process requires the sound card be connected to speakers with a proprietary Digital Input, or its analog out.
If your receiver has discrete multichannel analog connections, it is recommended that they be connected to the Analog Front-Out, Rear-Out, and Center/Subwoofer Out on the audio card. In this case, the Sound Blaster card will decode the AC3 files or DVD files, and output to appropriate speakers.