Actually I don't know of any other solution as for 3rd party DSP which can do the trick but it might be my ignorance only on the topic
I have also heard that their 1st attempt with 3Sixty was not too successful but the Mk II belongs to a whole different league.
Anyways, the output of the OEM radio has to be managed - you will see once the 3Sixty will be connected that the radio preset is far from being linear.
According to my guy the best solution would be adding a good radio-preamp (he has mentioned some Alpine and Pioneer models) - he even took a long look at the area of the panorama roof buttons there.... but I told him to chill

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X5 3.0d - Space Grey , Beige Leather, Burl Walnut Trim, SatNav, Rear Camera, Sunroof, Light Package, 19" 212 Wheels, Tint, Power Fold-in Mirrors. AUDIO: Morel Elate 6 Audiophile Speaker System with Genesis Dual Mono Amp and Rockford Fosgate 3Sixty.2 DSP