Same problem. I get DAB adapter for free with new leaf. But first problem as it was said long time between changing station and second problem and biggest for me: its use usb port! If you want to listen usb flash you must remove usb cable to DAB radio and connect usb flash. Its completely uncomfortable. I dont understand why its not possible to get some DAB module with some CAN bus connection like this:
http://www.handsfree.co.uk/images/products/connect2/AutoDAB.gif