Playback sound cannot be heard

1. Check the speaker connections and the volume settings on the speakers.

2. Adjust the E1x2 OTG Line output and headphone amp output volume.

3. Check the settings on the ToppingPro.

4. Connect E1x2 OTG and your computer directly without using a USB hub.

5. Remove the USB devices which are connected with your computer and not in use, and then confirm the sound.

6. Quit all applications you are not using then confirm the sound.