If there is DSP button in your factory radio, or your car has digital sound system like Harman-Kardon, you can buy this extension harness to modify the speaker connection
100% Brand New and High Quality
Plug and Play
6m long cable
Fakra radio plug
Fitment:
For BMW / Mercedes-Benz
Material: Plastic
Colour: black
Package Contents:
1 x Radio extension cable
Only the above package content, other products are not included.
Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.