How to obtain screen brightness control

sudo gedit /etc/default/grub

Add acpi_vendor=backlight , as follows:

GRUB_CMDLINE_LINUX_DEFAULT="splash acpi_backlight=vendor"

Then update GRUB

sudo update-grub2

Then reboot

How to gain a full Beats™ audio experience

sudo gedit /etc/modprobe.d/alsa-base.conf

paste this to the end as a new line:

options snd-hda-intel model=ref

reboot and enjoy improved audio!

After that enable brightness keys in Power Management like on the picture

taken from here