I recently bought a new aftermarket head unit for my 99 740i and i was talking to someone about install and they said that if my system was "amplifed" i would have to rewire all my speakers up to the headunit which would mean i would need professional installation, i was wondering if there was anyway to check and see if i have one of these amplifed systems which i assume is the harmon karmon, my vin is WBAGG8336XDN73872 if that helps anything. Thanks in advance.

I'm pretty sure if you give your vin to your local dealer parts dept they can tell you what you need to know.