Here we have the Micronas MAS 3529H Dolby Digital and Mpeg2 Layer 2 Audio Decoder. Its the heart of the sound card, without it, there would be no 5.1. Dolby labs made a contract with Micronas to manufacture these chips under specifications.
The MAS 3529H decoder IC acts as a complete implementation of 5.1 DTS and Dolby Digital/Pro Logic II decoders. On the chip’s 8-channel output an Lt/Rt or Lo/Ro downmix is available simultaneously to the multi-channel audio for recording or headphone usage.