I've tried a million different /etc/asound.conf configurations, and I can't get anything to work. My analog out works, but only one program can use it at a time. My digital out doesn't work at all -- the optical red light isn't even visible. Yet I get sound through it if I do:

aplay -D plug:iec958 /usr/share/sounds/startup.wav

Incidentally, if I watch the connector, it puts out that red light for a few seconds when it plays this, but then goes right back off.

**** List of PLAYBACK Hardware Devices ****
card 0: ICH5 [Intel ICH5], device 0: Intel ICH [Intel ICH5]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: ICH5 [Intel ICH5], device 4: Intel ICH - IEC958 [Intel ICH5 - IEC958]
Subdevices: 1/1
Subdevice #0: subdevice #0

I have had the SPDIF working before, with the analog part used for my VoIP headset, with a different configuration that I've lost at this point. But dmix never worked for either. Only one program could access each device at a time. Here's the latest /etc/asound.conf I've tried:

# Override the default output used by ALSA.
# If you do not override the default, your default
# device is identical to the (unmixed) analog device
# shown below. If you prefer mixed and/or digital
# output, uncomment the appropriate four lines below
# (only one slave.pcm line).
pcm.!default {
type plug
## Uncomment the following to use mixed analog by default
#slave.pcm "dmix-analog"
## Uncomment the following to use unmixed digital by default
# slave.pcm "digital-hw"
## Uncomment the following to use mixed digital by default
slave.pcm "dmix-digital"
}

# Alias for analog output on the nForce2 (hw:0,0)
# - This is identical to the device named "default"--which
# always exists and refers to hw:0,0 (unless overridden)
# - Therefore, we can specify "hw:0,0", "default", or "analog"
# to access analog output on the nForce2

pcm.analog {
type plug
slave.pcm "analog-hw"
}

# Control device (mixer, etc.) for the nForce2 card
ctl.analog {
type hw
card 0
}

# Alias for (rate-converted) mixed analog output on the
# nForce2 (hw:0,0)
# - This will accept audio input--regardless of rate--and
# convert to the rate required for the dmix plugin
# (in this case 48000Hz)
pcm.mixed-analog {
type plug
slave.pcm "dmix-analog"
}


# Control device (mixer, etc.) for the nForce2 card
ctl.mixed-analog {
type hw
card 0
}


# Alias for (rate-converted) digital (S/PDIF) output on the
# nForce2 (hw:0,4)
# - This will accept audio input--regardless of rate--and
# convert to the rate required for the S/PDIF hardware
# (in this case 48000Hz)
pcm.digital {
type plug
slave.pcm "digital-hw"
}

# Control device (mixer, etc.) for the nForce2 card
ctl.digital {
type hw
card 0
}

# Alias for mixed (rate-converted) digital (S/PDIF) output on the
# nForce2 (hw:0,4)
# - This will accept audio input--regardless of rate--and
# convert to the rate required for the S/PDIF hardware
# (in this case 48000Hz)
pcm.mixed-digital {
type plug
slave.pcm "dmix-digital"
}

# Control device (mixer, etc.) for the nForce2 card
ctl.mixed-digital {
type hw
card 0
}

# The following devices are not useful by themselves. They
# require specific rates, channels, and formats. Therefore,
# you probably do not want to use them directly. Instead use
# of of the devices defined above.

# Alias for analog output on the nForce2 (hw:0,0)
# Do not use this directly--it requires specific rate,
# channels, and format
pcm.analog-hw {
type hw
card 0
# The default value for device is 0, so no need to specify
}

# Control device (mixer, etc.) for the nForce2 card
ctl.analog-hw {
type hw
card 0
}

# Alias for digital (S/PDIF) output on the nForce2 (hw:0,4)
# Do not use this directly--it requires specific rate,
# channels, and format
pcm.digital-hw {
type hw
card 0
device 4
}

# Control device (mixer, etc.) for the nForce2 card
ctl.digital-hw {
type hw
card 0
}

# Direct software mixing plugin for analog output on
# the nForce2 (hw:0,0)
# Do not use this directly--it requires specific rate,
# channels, and format
pcm.dmix-analog {
type dmix
ipc_key 1634
slave {
pcm "analog-hw"
period_time 0
period_size 1024
buffer_size 4096
rate 44100
}
}

# Control device (mixer, etc.) for the nForce2 card
ctl.dmix-analog {
type hw
card 0
}


# Direct software mixing plugin for digital (S/PDIF) output
# on the nForce2 (hw:0,4)
# Do not use this directly--it requires specific rate,
# channels, and format
pcm.dmix-digital {
type dmix
ipc_key 1235
slave {
pcm "hw:0,4"
period_time 0
period_size 1024
buffer_size 4096
rate 44100
}
}

# Control device (mixer, etc.) for the nForce2 card
ctl.dmix-digital {
type hw
card 0
}