HT computers are not exactly down my alley, though, I do find them interesting.
In any case (ahem... one with PCI slots), BlueGears recently released an "ultimate" HTPC audio card. Merc likes BlueGears' earlier audio cards, which I believe he nominated as having the best-bang-for-the-buckaroo in audio cards.
Ultimate PCI sound solution for Gaming and Home Theater PCs. 8 Channels, 24-bit/192KHz, 110 dB Oxygen 8788 PCI sound card. Bluegears' b-Enspirer is a high quality PCI 8 channel sound that can be built into home audio electronics or personal computers to provide high fidelity sound playback and processing. b-Enspirer enables studio level audio performance. With support for 8 outbound streams, b-Enspirer can easily support the latest theater quality 5.1, 6.1 or even 7.1 surround sound systems. For enhanced playback, b-Enspirer enables the hardware that allows customers to experience the complete surround sound experience whether using four, or even two speakers...
http://bluegears.com/b-Enspirer.html