Logic 7 uses a fiber optic cable between the amp and Head Unit or Radio
instead of the standard analog stereo signals used by almost all aftermarket head units.
The fiber optic signal is proprietary that only the BMW head unit transmits
and the L7 amp receives. The l7 amp is designed to only receive this signal
No aftermarket Head Unit is designed to transmit this type of signal .
It is not a standardized format like in a home entertainment system
that uses some form of dolby multichannel fiberoptic signal.
This is why you have to replace the amp and possibly upgrade some of the speakers . people are mostly using and ms-8 to substitute for the amp and add on amps and speakers.