Portable Headphone AmplifierPHA-3

Listening to music with headphones via balanced connection

Connecting the balanced connection compatible headphones to the headphone amplifier upgrades sound quality from an audio device connected to the headphone amplifier.

Balanced connection compatible headphones

MDR-Z7, XBA-Z5, MDR-1A*, XBA-A2*, XBA-A3*, XBA-H2*, XBA-H3* (as of July 2014)

* The balanced-connection headphone cable (MUC-S20BL1/MUC-M20BL1) (sold separately) is required to connect MDR-1A, XBA-A2, XBA-A3, XBA-H2 and XBA-H3.

For the latest compatible models, access the following URL:


You cannot connect your headphones to the (headphones) BALANCED L/R jack when the device is connected to the AUDIO IN/LINE OUT jack. Connect your headphones to the (headphones) NORMAL jack.

  1. Connect the L plug of the balanced-connection headphone cable to the (headphones) BALANCED L jack and R plug to the (headphones) BALANCED R jack.

  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 flashes 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 using balanced connection with headphones that have low impedance (less than 16 ohms), the limiter prevents excessive output, which may cause the sound to be cut off. In this case, turn down the volume of the headphone amplifier.
  • If you turn the volume up too high, it may damage your hearing. Be careful not to turn the volume up too high.
  • Do not connect your headphones to the (headphones) NORMAL jack and (headphones) BALANCED L/R jack simultaneously.
  • 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)
  • Connect balanced connection compatible headphones to the (headphones) BALANCED L/R jack of the headphone amplifier properly. Otherwise sound quality will not be upgraded.