pcm6cast is a raw PCM audio streaming broadcaster and client using RTP over IPv6 Multicast. It is free open source software released under the LGPL.

Unlike VAT and RAT, which are designed primerily for audio conferencing, pcm6cast is designed to be used for audio distribution and broadcast.

http://www.ecs.soton.ac.uk/~njh/pcm6cast/

There is a test stream available from Southampton University: