The input end is designed with a balanced circuit, which can be single-ended input or balanced input. Single-ended input uses a large two-core mono plug, and balanced input uses a large three-core two-channel plug. Balanced can be used for long-distance transmission, and balanced for short-distance transmission. It doesn't matter, if you don't understand these just ignore them, can understand them. The output port is unbalanced single-ended and can use a 6.5mm large two-pin plug; 6.5mm, some people call it 6.35mm, and abroad it is called 1/4 inch; dual-channel amplification, gain adjustment (0-20DB), the two channels can be used alone or at the same time without affecting each other; Working frequency: 20HZ-20KHZ Input impedance: single-ended 10K, balanced 20K output impedance: 200 ohms Working voltage: DC 5V-12V static power consumption: 0.3W working current: 5V-73MA, 12V-30MA For 5V power supply, you can use a power bank or a high-quality charging head. Poor-quality charging heads will cause . size: about 10.8 x 4.2 x 2.7cm Material: plastic+metal colour: black Package Contents: 1 x amplifier 1 x Charging Cable Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.