Item Type: Headphone Amplifier Material: Metal Colour: Black Input Interface: Stereo 35mm TRS interface RCA interface Input Impedance: 22K ohms Maximum Input Signal Level: +22dB Output Interface: Stereo 1/4TRS interface 3.5mm TRS interface Output Impedance: Minimum 16 ohms Maximum Gain: 19dB Signal To Noise Ratio: >98dB Product Applicable Power Plug: EU Plug 220VAC 300mA Package List 1 x Headphone Amplifier 1 x Charger 1 x User Manual 1Scratch And Rust Resistance: Finely carved and polished metal texture with dust free spray paint process, scratch resistance and rust resistance, which are a pursuit of high value demeanor 2Meet The Needs of Up To 8 People: Four independent volume control, support stereo and mono switching, you can insert 4 6.35mm earphones and 4 3.5mm earphones at the same time, which can meet the needs of up to 8 people 3Each Signal Is Finely Amplified: This amplifier is the best combination of earphones, each signal is finely amplified, no interference, no crosstalk 4Stereo And Mono Switching: RCA lotus stereo input, 3.5mm stereo input, suitable for stereo and mono switching of various audio equipment, realize on the go listening 5High Performance: The minimum output impedance is 16 ohms, the maximum gain is 19dB, and the signal to noise ratio is more than 98dB