Sharpens the "phantom center" of the music on the dashboard.

Even with IMPRINT engaged, the Sound Manager often allows manual tweaking of time alignment.

Based on available information, here’s what this likely refers to:

Your ears will thank you. And now you finally know exactly what the "Sound Manager 21" is and how to use it.

The ISM 21 system consists of a measurement microphone and a sophisticated software algorithm. The microphone is placed in the vehicle, and the software measures the audio response at each seat. The data is then used to create a customized audio calibration file that adjusts the sound response to optimize the listening experience.