Right… When you record streaming audio, you’re capturing what’s coming out of your soundcard.
I assume you’re on a laptop? If you have external speakers you can plug them in and turn-down the analog volume, or plug-in a pair of headphones/earphones to kill the internal laptop speakers. Or, you could get a cheap USB soundcard and plug nothing into it.
Or, you can try one of the 3rd party applications on [u]this page[/u].