Features: Ultra-compact stereo headphone amplifier for studio and stage application. With 4 headphone output channels and 1 input channel. Volume of each output channel can be controlled independently. Provides highest audio quality for each headphone even at maximum volume. Ultra low noise 4580 operational amplifier for outstanding audio performance. Comes with a DC 12V power adapter. Specifications: Material: Metal Color: Silver/ Black(optional) Headphone Jack: 6.35mm (1/4") Item Size: Approx. 10.5 * 5.5 * 3cm / 4.1 * 2.2 * 1.2in Item Weight: 185g / 6.5oz Package Size: 14 * 10 * 8cm / 5.5 * 3.9 * 3.1in Package Weight: 323g / 11.4oz Package List: 1 * Amplifier 1 * Power Adapter 1 * User Manual (English)