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Fiber Optic MOST Adapter for AUDI/BMW/Mercedes-Benz/Porsche/VW
  • Model: MOST25-01

Price:   $149  $99
Save: 34% off

This Fiber Optic(MOST) adapter allows you to retain the factory AUDI/BMW/Mercedes-Benz/Porsche/VW MOST amplifier audio system when installing ANY aftermarket radios. In addition, the output from all speakers includes a subwoofer and premium sound quality. This makes for a nice clean, easy install.

When installing this interface into your AUDI/BMW/Mercedes-Benz/Porsche/VW, you must ensure that the fiber optic signal loop is not broken. In addition, if you have other devices, including the original CD Changer, satellite radio, and telephone module, they must consistently stay connected to the fiber optic signal loop.

To identify if you have a fiber optics MOST factory amplified audio system, you can check the vehicle in several 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 car was manufactured with an amplified audio system. If you are unsure, please send the VIN and a photo of your car's existing dashboard to, and we will help you check.

Compatible vehicles:


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

Mercedes-Benz C-Class(W203) 2004-2008
Mercedes-Benz CL-Class(C215) 2003-2006 
Mercedes-Benz CLK-Class(A209/C209) 2005-2009
Mercedes-Benz CLS-Class(C219) 2004-2006
Mercedes-Benz CLS-Class(C219) 2006-2010
Mercedes-Benz CLS-Class(C218) 2010-2012
Mercedes-Benz E-Class(W211) 2002-2006
Mercedes-Benz E-Class(W211) 2006-2010
Mercedes-Benz GL-Class(X164) 2005-2013
Mercedes-Benz ML-Class(W164) 2005-2011
Mercedes-Benz R-Class(W251/V251) 2005-2018
Mercedes-Benz S-Class(W220) 2003-2006
Mercedes-Benz S-Class(W221) 2006-2014
Mercedes-Benz SL-Class(R230) 2005-2006
Mercedes-Benz SL-Class(R230) 2006-2012
Mercedes-Benz SLK-Class(R171) 2004-2006
Mercedes-Benz SLK-Class(R171) 2006-2012

Porsche 911/977(2004-2015)+BOSE
Porsche Boxster(2004-2015)+BOSE
Porsche Cayenne(2003-2016)+BOSE
Porsche Cayman(2005-2011)+BOSE

Volkswagen Touareg (2011-2017)

Connection map

1. Yellow wire-Positive of battery(usually 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

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 only uses TWO RCA audio cables, how will I 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 Harman Kardon/BOSE amplifier will distribute sound to 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 only uses 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: to convert RCA audio into a fiber optic signal the factory amplifier can understand.

Payment Accepted



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  We offer worldwide shipping service by international
couriers like FedEx/UPS/DHL/EMS/Aramex etc.,
Orders usually be shipped within 1-2 working days and
the tracking number will be sent to you by system email.
For example, if you come from US, it usually takes about 3-5 business days to arrive your door after place the order.

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  • posted by Bill

    Device worked as advertised. Shipping was quick and simple. Installation was suprisingly easy.