Relaying ?

Could someone explain how the Relaying option works where you wish the IR server to relay a source from another server - will it for example allow us to relay http://myip:9001/stream.mp3 ??

Kind of yes but it depends on the server type. Shoutcast servers just require the IP/hostname and port.

We have an internal server running SlimServer and streaming on http://myip:9001/stream.mp3 - during testing yesterday we opened this stream in Winamp and then streamed it to your server but that adds an unnecessary step in my view - is it possible to open the stream direct from your server assuming that myip is publcly accessibale (which it is) ?

Im not familiar with SlimServer. You might like to try it out and see if it works with our servers.