The SK01 is a high-power headphone amplifier with tone controls (treble,middle and bass), high and low gain settings, bypass mode, and loudnessfunction. The tone control feature allows you to customize the sound to your preferences and compensate for any shortage in your headphones or audio system. The high and low gain settings are suitable for headphones with different impedance. The bypass mode provides a pure reproduction of the sound. The loudness function allows you to immerse yourself in the world of music during quiet nights. Highlight: Model: SK01 Input: 3.5MM line in Output: 3.5mm Headphone, 6.35mm Headphone, 3.5MM line out Powe Supply:5V Power Input Interface: USB Type-C : Less than 0.001% @ 1kHz and 770mV : equal 108dB Frequency response: 20Hz-20kHz (0.5dB) Amp output maximum power: High Gain: RMS 2400mw/ 32, Low Gain: RMS 300mw/32 Headphone matching impedance: 16-300 Colour:Black Material:Aluminum alloy Package Contents: 1x Sk01 Headphone Amp 1x 2-in-1 USB Type-A/C to Type-C 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.