2 Amplifier Inputs (INPUT SELECT) Headphone output terminal (1 each) is included. The volume can be adjusted, and it can also output simultaneously from both 0.2 inch (6.3 mm) or 0.1 inch (3.5 mm). Press 1 and 2 of OUTPUT at the same time to simultaneously output from both sides. The output to the speaker can be turned off by pressing the 0 OUTPUT SELECT.(When using headphones/earphones) *The 0.1-inch (3.5 mm) input terminal uses a slightly tighter lock. Note: This product is a selector that only supports stereo connection of an ordinary analog amplifier (earth (ground)Therefore, when using the headphone terminal with the BTL output amplifier with the balance connection may lead to noise and amplifier failure.Only the speaker selector part can be used when using the BTL output amplifier.Please acknowledge