When recording a radio stream, RadioLover can re-broadcast the radio stream on a local port on your computer. A port is identified by its number. Think of a television channel. This is how iTunes listens to a stream which RadioLover is recording.
Note that the recent release of iTunes 4.6 is exhibiting some strange behaviour when connecting to streams. If a stream has not connected properly in RadioLover, it is advised to not try to listen to the stream. We are investigating this issue.
If you prefer to listen with Audion 3, you can select this option and then Audion will be used instead of iTunes for listening to streams.