I suspect it is the same system that is offered in the S5 Aero. An amplifier and speakers, with a range of inputs. Me? I want a Bluetooth enabled DAB Radio, that is all. The lack of one could be a deal breaker.
Exactly what I would want too. That is exactly what I am thinking of fitting as a replacement of the existing radio in the Plus 4. I will probably fit a microphone for hands free calls, if only to answer and say hold on the till I find a place to stop.