After spending the last few weeks focused on this, I thought I'd write up my experiences in retrofitting a Columbus headunit with DAB to my Rapid. There's a lot of different posts scattered around so I've tried to collate as much as I can here.  Note that I have focused on Swing to Columbus, but most of the information here can be used to go from Amundsen to Columbus too.    I'm no good with terminology - what's a Swing headunit?   The Swing headunit was the standard opt