From a quick look, it's not a proper SHOUTcast provided stream & is using a custom server based on what it's reported as being.
That probably is why things are acting up but I've been out of that scene for too long now that I don't know who/what it would relate to & if there's any workarounds (e.g. url parameters that can be set).
I can't seem to get the stream to start playing irrespective of the in_mp3 plug-in settings as it just seems to hang & does nothing else. Replacing that plug-in since it's one of the last ones from Winamp 5.666 that I'm re-using is a goal for this year but I don't have an eta on when it'll be done. As I strongly suspect the issues seen are down to a combination of that plug-in & the server & they're not talking in the expected manner.
Sorry to say I don't have anything obvious I can do to get it working for you other than what you've already tried if that's working for you.
-dro