HDMI audio solution by a sound card with HDMI is a waste of money. The ultimate purpose of digital audio is convey the information 100% faithful to the original source to the AVR, and this can be achieved easily by any cheap graphics card with HDMI audio (or any onboard audio S/PDIF for S/PDIF). The supported audio formats by HDMI and S/PDIF are:
- HDMI: multichannel LPCM, Dolby Digital, DTS, Dolby TrueHD, DTS-HD MA/HRA (not every HDMI audio solution supports all of them)
- S/PDIF: stereo PCM, Dolby Digital, DTS
Dolby Digital, DTS, DTS-HD HRA are lossy (i.e. part of the information is permanently lost in compression), while Dolby TrueHD, DTS-HD MA are lossless (i.e. contains all the information of the original source). If you are concerned with quality, you'd better avoid S/PDIF. The exception is stereo music (well the majority of music sources are stereo); S/PDIF is perfectly fine for this and onboard audio codec's S/PDIF is perfectly fine. (Nevertheless I don't see a reason to use S/PDIF.)
The HDMI audio formats supported by a graphic card is here
A possible solution is:
- A graphics card with HDMI -> AVR (movies and music) & DVI (with a proper DVI-HDMI adapter for audio pass-through) -> TV (movies)
- A graphics card with HDMI -> TV (movies) & an analog sound card (e.g. ASUS Xonar Essence ST + Xonar H6) -> power amplifier (movies and music).
The former is simple and you will get good quality of audio in both movies and music via AVR. If you don't use AVR, you can still watch videos with TV. In the latter case, you use an analog sound card + amplifier for good music as well as movie. Here is a caveat: TrueHD/DTS-HD to LPCM is downsampled by a commercial BD player. A sound card with HDMI (Xonar HDAV1.3 and Auzen X-Fi HomeTheater HD are the only cards) without using HDMI is a solution to avoid it. Another caveat is that these cards are tied to a particular BD player (Xonar to TotalMedia Theatre, Auzen to PowerDVD). So you will lose freedom.
Stutter-free dual 1080p video stream via DXVA is possible with HD 5750 or higher. A DXVA stream + a non-DXVA stream is possible with any card (non-DXVA means you need a dual-core 2.5GHz or higher CPU). Dual HDMI audio stream is not supported by HD 5xxx.