Hi,
I had a look at an "add on" unit 18 months or so ago.
Thread here:
https://the75andztclub.co.uk/forum/s...&highlight=dab
Abandoned as the results were not as good as FM.
However, DAB has doubtless come on since then and I've been in several newer cars - including a 2010 BMW 320D - with DAB as standard and they were fine.
Maybe a chat with Jubarelly would be worthwhile? He'll be the guy who knows what's what.
Andy.