Thanks for that John. Are the DRLs wired directly to the car's loom or is there some sort of "driver" involved? If the latter it might be that it, or the wiring to the LEDs, needs screening.
Of course the simplest solution is to dispense with the DRLs. Changing the radio receiver and aerial system is a lot of work for what could be considered a fashion accessory.
Also, do you have a guarantee that the Blaupunkt DAB unit won't be similarly affected?
Simon