StationRipper doesn't actually have a music player - it just uses the default music player on your machine.
If you try to listen to a recording station, and can't hear anything, then it is most likely that your default music player isn't set up to handle defaults correctly.
The simplest thing to do is to go into your player and tell it to reset to re-associate with music files. StationRipper specifically tells windows to launch whatever is associated with m3u files.
If that doesn't work, then you can get
WinAmp, which is a free music player, which usually will work.
NOTE: Shoutcast, Last.fm and Podcasts can be listened to while recording. Anything using the StationSniffer (including Pandora) are not.