The external pin header (J7) can be connected to an audio device that supports SPDIF or I2S.
Note that the header pins are not mounted by default.

Pin Information

Name PIN
GND 1
SPDIF Output 2
5.0V 3
I2S MCLK 4
I2S LRCLK 5
I2S SCLK 6
I2S Data Output 7

Square soldering pad is Pin #1 as below picture.

How to use

It is recommended to solder the pins for easy use.

Android

ODROID Settings helps you to select an audio interface - HDMI, Lineout (3.5mm audio jack), SPDIF or I2S - supported by the ODROID-N2.
After selecting an output device, your selection will be applied to the device after a few moments.