Thanks for the input guys, I am going to price out these cards and see what I can do. I will let you know how it goes.

I'm using an Nvidia GT460 which required me to compile Alsa 1.04 for MD. The card is an MSI Twin Frozr that has two large but quiet fans against the Heat Pipe cooling. This really opened up the full audio capabilities of my Rotel RSP-1570

Where it gets tricky is figuring out which one of the several HDMI streams is actually communicating with your TV or Surround processor and then adding it to /etc/modprobe.d/dist-alsa.conf. Mine ended up being:

options snd-hda-intel enable_msi=0 probe_mask=0x102.

I had to use cat /proc/asound/card0/ and go through the eld's and codecs until I saw my Rotel Surround processor. It's best explained here:

ftp://download.nvidia.com/XFree86/gpu-hdmi-audio-document/gpu-hdmi-audio.html

In addition, so that programs other than Myth can use the output directly to HDMI, especially important for Flash videos within Myth, I added this to /etc/asound.conf:

pcm.!default {
type hw
card 0
device 3
}

I've found that most documentation on asound.conf is outdated and/or wrong. Even Alsa's own documentation.

If your device happens to use the first codec and eld it finds then you are very lucky. Mine was number three in both cases. Once the modprobe argument is added, then you will only see ONE eld and codec which works and will be numbered as 1 at this point. Eventually there will be a fix for better detection and automatic device node creation for usable HDMI streams but for now, none.

Other thoughts: The latest kernels contain the latest Alsa out of the box. I've been able to play up to 24/192 FLAC files via MythMusic, also 24/96 and 24/176.4 but NOT 24/88.2. I can play 24/88.2 with any music program outside of the Myth frontend and it shows 88.2 on my processor's display.

There is some misinformation as to what bitrates the Intel HD audio contained in the GT4xx will support. I am here to say that nothing is missing from 16/32 to 24/192 with PCM and can handle several surround sound standards up to 8 channel uncompressed up to 192khz. It's still weird that Myth cannot handle 24/88.2 in MythMusic. Probably just overlooked in the code.

Oh, yes you need PCI-E. Consider AGP as dead and you won't have a problem selecting cards.

Nvidia G210 with 512MB is all you need. :-)

There are a couple of brands that have a passively cooled low profile version.

With Mythdora 12.23 you need to download the later ALSA Drivers package from the alsaproject website and compile it before it shows up in Alsamixer.
I can never get the Myth 0.24 "automatic" detection to work properly and I end up specifying the device but otherwise sound works fine.

The G210 (and GT220 I think) maxes out at Advanced 1x at 1080p but I believe the display needs to be double frame rate input to handle 2x anyhow...

Cheers
Ian

I'm running a Nvidia GT240 (Gigabyte) works well although with the older alsa drivers/libraries its not all that automatic, I believe the GT430 is the currently mythtv recommended graphics card.

Cheers