i have an idea for 9200 & 9100 sounds if you have sound system in car without aux in and you want to listen music from navbox in your car sound system not from mono speaker.
my idea is connect mp3 fm player connected to preamplified SPK output of navigation box.
then lesin all navbox sounds from your radio fm.
like this pic.
imagine your iphone is your navbox
think and try and enjoy