Porsche (->2012) interface "Turn - On" for OEM amplifiers (ACV, MOST-RCA).

Porsche Cayenne, 911, Boxster, Cayman (->2012) with MOST25 adapter "Turn-On", OEM amplifier will be retained (MOST-RCA).
ACV 13-1190-52

Active system adapters maintain the function of the original Soundsystem. 
They enable the installation of standard aftermarket radios to the active speakers.

Optical fibre analog converter for Mercedes and Porsche vehicles equipped with MOST25 (optical fibre) active sound system.
With this adapter you are able to install an aftermarket head unit with rca preamplifier outputs.
The OEM MOST25 (fibre optic) amplifier will be retained.

Mercedes M-Class, W164 (2005-2011), 
Mercedes GL- Class, X164 (2005-2011), 
Mercedes R-Class, W251 (2005-2011), 

Porsche Cayenne (2002-2010), 
Porsche 911, 987/997 (2004-2012), 
Porsche Boxster (2004-2008), 
Porsche Cayman (2005-2009)... 

* Note: 
Fader front/rear not supported.
Porsche 911 / Boxster (986/996): not suitable for YAZAKI optical fiber connectors used in early 996 / 986 models with MOST System
Not compatible for Mercedes vehicles with D2B optical bus system (Comand2.0 & Comand2.5).