I followed Asbojohn's route - and spec.
As I listen mostly to pre recorded music (rather than radio) I use a DAC player. It's hand-held, so
the passenger DJ can see what they're playing. The extra grunt of the DAC puts some depth into the sound... so you can actually hear it on the open road.
I suppose I could also put the DAC straight into the AUX socket in the glovebox, which I presume goes straight into the factory fit amp in the footwell.
Will