Fiat 2016 500L Uconnect 6.5 Owner's Manual Supplement page 28

When Surround Sound is On, you can hear audio coming
from every direction as in a movie theatre or home
theatre system.
Loudness
Press the "On" button to activate Loudness. Press "Off"
to deactivate this feature.
When Loudness is On, the loudness setting increases
dynamic range of audio at higher volumes.
AUX Volume Offset
Press the "On" button to activate the AUX Volume Offset.
Press "Off" to deactivate this feature.
RADIO MODE 27
3