I have a 2010 535i without the upgrade stereo package. I like to add a sub woofer, but was told that I cannot unless I re-wire the car with cooper wire, since the car stereo is wired with fiber. Is there a way to add the add the sub woofer to the current setup? I called my BMW dealer and they do not do sub woofer add on.
TIA...

Did you try this:
https://5series.net/forums/index.php...search_in=core

- Antti -

The factory audio system does not have preamp outputs, so you will need to purchase a line-level converter. This device takes the speaker-level output from the factory amplifier and converts it to a preamp level signal which can then be plugged into an aftermarket amplifier. At that point, you add an amp and the subwoofer and you're all set.

If you visit a custom audio shop they will know about line converters and can advise on which one is correct for your situation.

Thanks!! I did not know if the factory system has a preamp out.

Will the line-level converter works on a fiber speaker output from the factory amplifier?

In my Logic7 system in my E60 545i, the amplifier is located in the trunk on the driver side. We used the speaker-level outputs from that amp to hook up my Audison BitOne processor, which acts as my line converter. Works perfectly.

i had a shop put in a sub woofer in my 545i and now my 550i..??