You definitely want the Belkin. Here's why:
•Only one cable into the armrest (from the power adapter, you need a short mini to mini cable, available at radio shack)
•Adjustible volume to raise the input level (which you WILL need)
•It FITS the e90
•It's available in BLACK:
http://catalog.belkin.com/IWCatProdu...duct_Id=193794