Aerophone AE-20, AE-20W: Why do the built-in speakers stay on when headphones are connected?

The Aerophone AE-20/AE-20W built-in speakers remain on by default, even when headphones are connected to the PHONES jack. To mute the built-in speakers automatically when headphones are connected, set "Speaker Setting" to "Auto."

1. On the scene screen, press the [MENU] button.
2. Use the [-] [+] (◀/▶) buttons to select “Speaker Setting” in the System parameters. and press the [MENU] button.
3. Use the [-] [+] (◀/▶) button to select “Auto.”
4. Press the [SCENE] button or turn the [SCENE CATEGORY] knob to return to the scene screen.