Raspberry Pi

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Sound

Get a cheap USB soundcard: "Creative Sound Blaster"

List sound devices:

cat /proc/asound/cards

List only names:

cat /proc/asound/card*/id

Change volume, select USB sound card with F6, caution: the sound blaster can be very loud on your headphones.

alsamixer

Save volume:

sudo alsactl store

Play wav file on external device:

aplay -D plughw:1,0 test.wav

JACK Audio Connection Kit

"Who is Jack, and what is it that Jack does?"

On a headless raspberry pi (assuming raspian distro), we need a trick to start jack WITHOUT an X session, for this we'll need a small script.

Make sure to replace U0x41e0x30d3 with your device name, that you get via the above mentioned command to list devices.

Also you might want to change the other parameters (sample rate, frames, ...)

#!/bin/bash
export DISPLAY=:0
export `dbus-launch | grep ADDRESS`
jackd -P70 -t3000 -dalsa -dhw:U0x41e0x30d3 -r44100 -p1024 -n3 -s

Send Audio to the Raspberry Pi over LAN

This assumes that you are running jackd (check section above).

sudo apt-get update
sudo apt-get install jacktrip

Check out the jacktrip documentation.

Make sure, jackd on your computer has the same settings as defined on the raspberry (ie the settings you just put in the above bash script).

On your computer, start jacktrip as server (don't forget to start jackd first, if it's not running already.):

jacktrip -s

Start jacktrip on the raspberry pi (exchange YOUR_SERVER_IP_HERE with your IP, doh!):

jacktrip -c YOUR_SERVER_IP_HERE