WARNING! To avoid hearing loss or damage, do not insert the Thinklabs earbuds into your ears until you are sure the volume on the One has been set to a moderate level.
STEP 1: Press any of the four control buttons for two seconds to power on the device. When the LEDs come on, release the button.
When the device comes on, the Battery/Volume LED will display the current volume, as shown below.
STEP 2: To increase the volume, press the Plus control button on the right. To decrease the volume, press the Minus button on the left.
NOTE: Please make sure your wired headphones are plugged all the way in to the 3.5mm jack on the One to avoid issues and to provide you with the best sound possible.
As you increase the volume, the LED will move to the right on the Battery/Volume Scale. Similarly, as you decrease the volume, the LED will move to the left, as indicated by the arrows in the following images.
NOTE: Pressing and holding the volume buttons will quickly increase or decrease the volume on the scale to maximum/minimum levels. Use caution when performing this function to avoid hearing damage.