Acura 2010 MDX - Manual (Page 317)

Rear Speakers
When you turn on the system, the
rear speakers are automatically
turned off if the rear system selects a
different entertainment source than
the front system. You will see the
Rear Speakers Off icon both in the
audio display and the overhead
screen. The sound for the rear
system is sent to the wireless
headphones. If you want to turn the rear speakers
on again, press and hold the REAR
PWR button until the Rear Speakers
Off icon goes off.
NOTE: The rear speakers are
connected to the front system, so
they will always play the source that
the front system is set to.
Rear Entertainment System
310