VLC is a free open source cross platform media application. It plays and streams almost every media format known to man. I am using VLC streaming to achieve whole house audio. I have several Ubuntu PCs connected to audio receivers throughout the house.
To get them all playing the same song I fire up VLC on my server where all my media resides with the following command:
vlc /var/lib/mythtv/music/ --sout udp:188.8.131.52
On each client I issue the following command:
That is all there is to it. I now have four stereos all playing the same tune. Whole house audio is great for parties or Saturday chores.