Okay. I sorted the local streaming thing.
Of course, it was really a case of RTFMS!!! Oh well ...
The problem was I couldn't link the Sangean to my wlan SHOUTcast broadcast. The Noxon radio has its own configurable webpage on the device to facilitate this.
The Sangean stores its stations and streams on the Reciva server. So you need to register the radio with Reciva.com - the radio's configuration menu tells you a unique registration number. You will then have your own login and a number of tools including "My Streams".
Give your stream a name if it doesn't already have one and its local address which will be something like http://192.168.xxx.xxx:8000/listen.pls.
You then have to force a station update on the Sangean by unplugging it from the mains for a few seconds and switching back on. Your stream will then appear on the menu at Radio Stations >>> Genre >>> My Stuff.
After all that, it works very well.
The .ogg thing has yet to be sorted. However, all audio files are transcoded to +AAC format on the stream so at least I can hear them that way.
*See my hifi index here.