You also need to use a 1:1 audio transformer to isolate your Mac Electronics from your scanner radio electronics.
Could you please elaborate? I don't have anything special in my setup.
What I have:
Motorola GP-68 with stereo audio cable connected to headphone-out jack
Other end of stereo audio cable connected to line-in on Mac
Nicecast setup as described in above wiki article except I have stereo instead of mono selected (as I'm using a stereo cable)
I realize mono is the recommended route, and I will switch as soon as I get the cable, but this works fine as-is.
Ben