I have an EVGA 590 SLI AMD mainboard with onboard Realtek HD Audio.

The headset works great but if there is support for the optical output I can't find it. This would be a real Linux killer for me if I couldn't pipe my music out to my reciever.

Interesting post. Sorry I haven't got the answer (yet) but your post made me curious, because I have a similar motherboard, by MSI, with the Intel HDA also on it. Mine claims to have 'automatic jack detection' which apparently detects when stuff is plugged into the sound ports.
I don't know how they might detect if something is connected to the optical output, but:

If you go into alsamixer, do you see any slider or control in there relating to the optical port? Do you see a slider (a control) for ALL of your audio ports?
Now, if you or I were to go ahead and connect some other stuff to the audio ports, I wonder if the alsamixer panel would show anything different?

Probably not, but who knows. Either way, my interest is piqued, and if I find anything useful on the subject, I'll be sure to post it. You'll have to test it though as I only have your standard issue desktop speaker set!

Sasha

UPDATE: The optical output is apparently the IEC958 control in alsamixer, which I do see on my alsamixer panel. I can enable and disable it, but again, have no way of testing whether it does anything.

http://ubuntuforums.org/showthread.php?t=712813

http://www.linuxquestions.org/questi...al-out-631414/

These two links seem to have the info you are looking for.

SVA

I installed the Linux package off the realtek site to see what sort of functinality it would provide and now my ubuntu install won't boot. Or rather when I log in as user I get kicked back out to the log in screen. The error message lists a *.so file (don't recall the exact name) that was easily identified as a sound component even to a novice like me.

When I get home from work I'll get it back to the original Alsa files and look at your info then post the results.

I was able to locate my iec958 output by running alsamixer at the command line and unmute it. It wasn't visible from the volume control available from the system tray (or w/e its called in gnome).

The next step is to enable PCM passthrough. When playing music from windows my reciever registers a dolby signal and with these settings prologic is coming on so the surround is being synthesized by the reciever not passed through.

1 step closer!

also I found this page which seems to have a lot of good info
http://alsa.opensrc.org/DigitalOut

Its unfortunately sketchy on the PCM passthrough.

Never compile and install software from Realtek for Linux. It will not work well.

A few commands to try.

mplayer -ao alsa:device=iec958

mplayer -ao alsa:device=spdif

mplayer -ao alsa:device=hw=0.1

For old programs that uses OSS, you may have to use /dev/adsp.

For DVD movies, use the following command

mplayer -ao alsa:device=iec958 -ac hwac3

Outputting to digital will take some time and it will not be as reliable as analog.

Always use alsamixer to change the volume. To see more controls in alsamixer, type alsamixer -V all.

FYI, Linux does not process stereo or mono for surround, so you have to select it in your amplifier. For music, it is best to use two channels.

BTW, I do not have a digital to analog converter box to test out digital from my Audiotrak Prodigy 7.1.