Oppo HA-2 - Manual (Page 5)

Names and Functions of Parts
Top:
1. Power/Volume Knob: Turn this knob clockwise to turn
on the unit and increase the volume. Turn it
counterclockwise to decrease the volume. Turn it
counterclockwise until it clicks to turn off the unit.
2. Power Indicator: A green light indicates that the power
is on. The light also serves as a reference point for the
scale on the Volume Knob.
3. Audio-in / Line-Out Jack: When the Source Selector is
set to “C”, this jack can be connected to an analog
audio source, such as a portable music player. When
the Source Selector is set to “A” or “B”, this jack acts
as the line-out for the USB DAC.
3. Headphone Jack: Plug your headphones into this jack.
CAUTION: Always reduce the volume before plugging
headphones in and putting them on. While wearing
headphones, do not connect or disconnect them.
Doing so could result in a sudden loud noise that could
harm your hearing.