[gentoo-user] Intel High Definition on-board sound controller - optical out working?

[Denis]

I have an optical out on my on-board Intel Hi Def audio controller
(also an Intel motherboard) and wanted to route the optical output to
my receiver, so I could play internet radio on my home audio system.
I got everything plugged in, but the receiver didn't pick up any
signal (I made sure all the right settings are selected on the
receiver).

So my question...  Is optical output supported in ALSA and the driver
for Intel High Definition audio controller?  Do I have to compile with
any specific flags to get it working?