Welcome to Bimmerfest?
Have you searched this forum at all? I posted about my AUX input installation just eight days ago. I indicated which part numbers I used and the part number I should have used because it's cheaper but appears to be exactly the same thing. Bottom line the AUX input I installed in my 2006 Z4 is working fine.
Mine: 2006 Z4 Roadster (E85) | Interlagos Blue Metallic | Black Extended Nappa Leather | Carbon Leather Trim | Purchased 7/19/12
Hers: 2011 335is Coupe (E92) | Le Mans Blue Metallic | Black Dakota Leather | Dark Glacier Aluminum | 6MT | ED 5/12/11
Also Mine: (On Order) 2016 M4 (F82) | Sakhir Orange Metallic | Black Full Merino Leather | CF Trim | M DCT | Adaptive M Suspension | 19" Black Alloy Wheels | ZEC | ZLP | ZDB | ED 5/13/16