Amazon.com : Mini White HDMI to 3RCA Composite AV Converter For TV/PC/PS3/Blue-ray DVD : Video Converters : Electronics

this one will call for a power source... I used this one, hardwired

DC 12V to 5V 3A 15W Waterproof DC Converter Mini USB Car Power Adapter | eBay

also, here is a link to the RCA-to-3.5mm cable

New Audio 3 5mm Male to 2 RCA Audio Y Converter Aux Auxiliary Cable SPC 1693 | eBay


my German sucks (non-existent!!) but i think this one talks about Video Overlay Mode, which is what we need... audio independent of video... About 60 euros... but you have to check with the seller about shipping to US and if he will remove the VAT (in europe about 20%) for non-EU sales...

BMW TV Freischaltung TV Free E38 E39 E46 X3 X5 Z4 und Range Rover 2002 | eBay