I'm still not clear about exactly what is currently in my X5. AFAICT there is NO external amp, so the radio module powers the speakers directly. Is this something BMW do for basic stereo in the UK?

Are BMW's external amps 'booster' amps, IOW do they use speaker level inputs and simply boost that a bit, rather than using line level inputs? Are they all like this or just some configurations?

Can I access the line level signals at all?

Even if I have no amp, will all the speaker signals be routed via the rack by the CD Changer? What about line level?

Before I can figure what I want to do, I need to establish what is currently there, so some help would be much appreciated. Particularly because UK options seem quite different to US ones.

Thanks.