How to record system/internet radio on iMac?

I want to record audio that comes from my Mac, audio that usually comes out of my iMac's speakers, either built in or ones I have connected to iMac's headphone socket outlet.

I used to use a piece of free software called Soundflower coupled with QuickTime, however, Soundflower doesn't seem to work anymore since system update, spent two hours with latest version trying to configure it to record a section of radio of a station I've recorded off in the past.

So, question is, is there a different piece of software that allows 'screen capture' but only for the audio, don't need video. Or do I have to use hardware?

Thanks all.