Portable Headphone AmplifierPHA-3

Listening to music with headphones

You can listen to music from an audio device with your headphones via the headphone amplifier. Follow the steps below when you connect the headphones with the stereo mini plug to the headphone amplifier.

  1. Connect the stereo mini plug of your headphones to the (headphones) NORMAL jack of the headphone amplifier.

    If you connect the headphones which has the L-shaped stereo mini plug to the (headphones) NORMAL jack, position it so that its cable is on the right side of the jack, avoiding the ridge on the left of the jack, and ensure the plug is fully inserted.

  2. Connect an audio device to the headphone amplifier.
  3. Set the INPUT select switch to the position where the port that your device is connecting to.
  4. Set the OUTPUT select switch to “.”

  5. Rotate the power/volume knob clockwise to turn on the headphone amplifier.

    The POWER/CHG indicator flashed in green and then lights up.
    Rotate the power/volume knob further clockwise to turn up the volume.

  6. Start playback on the connected audio device.

    When playing High-Resolution Audio format files on your computer with the headphone amplifier, download and install “Hi-Res Audio Player.”

  7. Rotate the power/volume knob to adjust the volume.

When the volume remains low

Depending on the headphones, the volume may remain low, even if you turn the volume up to the max volume.

In this case, turn off the headphone amplifier and set the GAIN select switch to HIGH, then turn on the headphone amplifier again. In normal use, the GAIN select switch should be set at NORMAL.


  • When the headphone amplifier is turned on, you can check the battery level by the number of times that the POWER/CHG indicator flashes in green.
    • Flashes three times: Substantially charged
    • Flashes twice: Half charged
    • Flashes once: Battery level is low. It is necessary to charge the battery.
    • Always flashing: It is necessary to charge the battery. If you continue to use the headphone amplifier without charging, it will turn off automatically.
  • When connecting a device such as a smartphone or portable audio player, adjust the volume on the connected device beforehand. Depending on the device, audio output settings may be required.


  • The headphone amplifier does not support monaural headphones, headphones with a remote control, or headsets with a microphone. Do not attempt to connect these devices to the headphone amplifier. It may cause malfunctions.
  • If you turn the volume up too high, it may damage your hearing. Be careful not to turn the volume up too high.
  • In the following cases, the relay in the internal circuit will make a sound.
    • When the unit is turned on
    • When the OUTPUT select switch is moved
    • When the INPUT select switch is moved to/from the position of the AUDIO IN/LINE OUT jack (right edge position)