Fiio R7 Manual page 24

R7 power adapter power supply voltage support between 100V to 240V AC
power
When you use the AC power supply, please turn off the AC power switch first.
Then toggle the AC/DC power switch to AC, and turn on the AC power switch.
DC power input: external DC power supply, 12V-3A
The R7 can also be used with external DC power supplies, such as the FiiO
PL50 linear power supply or other power supplies to give your sound an even
purer, blacker background to truly make the musical details pop.
When you use the DC power supply, please toggle the AC/DC power switch to
DC.
Power on:
After connecting to the power supply, short press the power button for 2
seconds to turn on the R7.
Shutdown:
Long press the power button,then click the power icon in the upper right corner
of the screen. Click shutdown to turn off the R7.
Introduction to system settings menu
Here is the system settings menu of the R7