PulseAudio

Be sure to configure ALSA first.

PulseAudio configuration

File: /etc/pulse/default.pa

Depending on your external AV-Reciever this prevents crackling sounds and outputs a continous a52 signal through S/PDIF

### Automatically suspend sinks/sources that become idle for too long
#load-moduleload-module module-suspend-on-idle

File: /etc/pulse/daemon.conf

Set correct sample-rate and channels

default-sample-rate = 48000
default-sample-channels = 6

Fix the default PulseAudio/ALSA a52 5.1 profile detection

File: /usr/share/pulseaudio/alsa-mixer/profile-sets/default.conf

Change any occurance of a52:%f to a52:

[Mapping iec958-ac3-surround-40]
device-strings = a52
channel-map = front-left,front-right,rear-left,rear-right
priority = 2
direction = output

[Mapping iec958-ac3-surround-51]
device-strings = a52
channel-map = front-left,front-right,rear-left,rear-right,front-center,lfe
priority = 3
direction = output

Setting the default device (to avoid default output pointing to analog headphones)

First you need to find out the device names by running:

# pacmd list-sinks | grep "name:"

# pacmd list-sources | grep "name:"

And then add them to the default.pa configuration:

File: /etc/pulse/default.pa

### Make some devices default
set-default-sink alsa_output.pci-0000_01_00.1.iec958-ac3-surround-51
set-default-source alsa_output.pci-0000_01_00.1.iec958-ac3-surround-51.monitor