This is from bmw car configuator
820
Loudspeaker system – harman/kardon surround sound
The harman/kardon surround sound system produces an extremely harmonious sound that reproduces voices, instruments and musical subtleties precisely and naturally. The system’s main features are the highly efficient 464W digital amplifier with nine channels and individually adjustable equalising. Its fully automatic and speed-dependent control function finely offsets the influence of any driving noise on the individually perceived volume. The 16 speakers create a full, consistent sound at every seat. Optional for M Sport models.