BMW/Mercedes-Benz/Porsche Fiber Optic MOST audio Adapter(BOSE and Harman Kardon)

This Fiber Optic(MOST) adapter allows you to retain the factory(Mercedes-Benz/Porsche/BMW) MOST amplifier audio system(Harman/Kardon or BOSE) when installing ANY aftermarket radios. The output from all speakers including subwoofer and premium sound quality. This makes for a nice clean easy install.

When installing this interface into your Mercedes-Benz/Porsche/BMW you must make sure that the fiber optic signal loop is not broken.  If you have other devices which can include the original CD Changer, satellite radio, and telephone module they must stay connected to the fiber optic signal loop consistently.

To identify if you have a fiber optics MOST factory-amplified audio system, you can check the vehicle in a number of ways. Some vehicles will have clear markings on the speaker grills indicating the presence of an upgraded audio system. You can also check with the original order notes/invoice from when the car was purchased from the factory, the upgraded sound system with an amplifier would show on the options list. If unsure, you can call your local dealer with your vehicle's chassis number and ask them to check if the vehicle was manufactured with an amplified audio system. If you are not sure, please send the VIN and a photo of the existing dashboard of your car to info@sigmacarstereo.com, and we will help you to check.

1. Please provide the 17 digits of your VIN(vehicle identification number).
2. Please photograph the car's current dashboard(radio system).
3. Does the car have a factory-installed external premium audio system? If yes, can you photograph the symbol on the door speaker grill?
4. Please photograph the car's current steering wheel

NOTE:  This does NOT support the D2B fiber optic system. If your fiber optic cable has these D2B connectors our MOST interface will not work.

This product has three models for different cars, so please make sure you provide the correct information of your car when placing the order to avoid mistakes.

Version 1:
Mercedes-Benz CL-Class 2003-2008
Mercedes-Benz CLS-Class 2003-2008
Mercedes-Benz E-Class 2002-2008
Mercedes-Benz S-Class 2003-2008
Mercedes-Benz SL-Class 2003-2008
Mercedes-Benz SLK-Class 2004-2008

Version 2:
Mercedes-Benz C-Class 2005-2008
Mercedes-Benz CL-Class 2009-2012
Mercedes-Benz CLK-Class 2005-2008
Mercedes-Benz CLS 2009-2012
Mercedes-Benz E-Class 2009-2012
Mercedes-Benz GL-Class 2005-2011
Mercedes-Benz ML-Class 2005-2011
Mercedes-Benz R-Class 2005-2011
Mercedes-Benz SLK 2009-2012
Mercedes-Benz S-Class 2009-2012
Mercedes-Benz SL-Class 2009-2012
Porsche Boxster 2005-2011
Porsche Cayenne 2005-2011
Porsche Cayman 2005-2011
Porsche 977/911 2005-2011

Version 3:
BMW 1 Series (E82/E87) 2008-2012
BMW 3 Series (E90/E91/E92/E93) 2006-2011
BMW 5 Series (E60/E61) 2004-2010
BMW X1(E84) 2009-2015
BMW X3(E83) 2003-2010
BMW X5(E70) 2006-2013
BMW X6(E71) 2008–2014
BMW Z4(E89) 2009-2016

 Connection map:

1. Yellow wire-Positive of battery(usually it is the yellow wire from the aftermarket head unit main harness).
2. Red wire- ACC wire(usually it is the red wire from the aftermarket head unit main harness).
3. Black wire-GND(usually it is the black wire from the aftermarket head unit main harness).
4. RCA audio input connects to the Front left and Front right audio output of the aftermarket head unit
5. Fiber optics plug connects to the fiber optics plug on your car

Connection diagram: here

Frequently asked questions:
Q.  Can I return this for a refund if I do not like it?
A:  NO.  We warranty the product for one year.  If there are any problems with it, we will replace it with a new one for you.

Q.  Why are there only TWO RCA inputs?
A:  It only supports stereo input from your front Left and Front Right RCA audio output.

Q.   If it is only using TWO RCA audio cables how will get sound from all of my speakers?
A:  The MOST interface will convert the TWO RCA audio signals into a fiber optic signal your factory amplifier can understand.  Your Harmon Kardon amplifier will distribute sound to all of your speakers including your subwoofer.

Q.  Can I control fade and balance after this is installed?
A:  You can control only LEFT RIGHT balance since it is only using those two RCA audio cables.  No fading from front to back.

Q.  Does this support steering wheel button controls?
A:  This does not add or remove the steering wheel button control.  It only has one function and that is to convert RCA audio into a fiber optic signal the factory amplifier can understand.