Sorry crunchmeister, but with those CB (i have them but a older version) the big plug is for speaker and the smaller one is for mic.
Mine come with those earbud:
http://www.cobra.com/images/productI...ndheld%202.gif
They work pretty well
Also I have test them with some other canadian tire's radio, they work fine. Also a guy have a more military style radio and I can ear him and talk with him but I don't know what radio he was using
EDIT: GRILLED....