you are right: there is no EQ function available for the user.
But the headunit has 2 fix presets:
- Standard-Preset: high frequencies are boosted to compensate the missing tweeters (cars without option S676 "BMW Hifi" only have midrange speakers mounted in the doors and subwoofers mounted under the seats)
- Hifi-Preset: high frequencies are not boosted (because cars with option S676 "BMW Hifi" have additional tweeters)
The parameter "AUDIO_SYSTEM_CIC" defines wich preset is used.
By the way: my car is F20 (build date: May 2014) with BMW Standard Hifi (no tweeters). I want to put in some aftermarket tweeters.
Therefor the Preset of the headunit should be switched to "Hifi-Preset" .