[AdrianSi]

With regards to the 'sat nav' connectors, I think is to do with the headunit outputs (pre-amp) as the Pro nav outputs are greater. I remember reading somewhere on here, I think it was on the global e90post Audio section, where somebody had taken the crossover units apart to work out exactly what they're doing. As I remember there are two seperate circuits within the units. I will try and uncover this thread and post it back here.