Item Features: Audio Input: 4 groups of RCA Audio Output: 2 groups of RCA/Headphone Jack Frequency Response: 20Hz-20kHz Treble&Bass Range: 6dB THD: 0.04% typical Operating Voltage: 12V SNR:100dB(20Hz-20kHz) Input Sensitivity: 0.775V Headphone Output Impedance: 32-300 Maximum Headphone Power: 160mW/32 Dimensions (W*D*H): 145*85*85mm / 5.71*3.35*3.35in Packaging Dimensions (W*D*H): 250*185*120mm / 9.84*7.28*4.72in Net Weight: 575g/1.27lb Packing Weight: 900g/1.98lb Features: Tube Preamplifier & Audio Switcher & Headphone Amplifier: 4 groups of RCA inputs, 2 groups of RCA and 3.5mm headphone outputs, both as an audio selector and splitter, no need to repeatedly plug and unplug cables; compatible with many audio devices such as computers, phones and CD players, etc., greatly improves the sound quality of your sound system. Mysterious built-in tube design: plug-in Soviet 6H3N tubes filter all digital feelings, the sound is warm and smooth, clear and delicate, all details are vividly presented to provide a live listening experience; classic NE5532 op amp, can easily drive most headphones. Independent tone control and input selector: With separate control of treble and bass, the specific proportions of high and low frequencies can be adjusted to present music with thrilling highs and deep lows. Also with the input switching knob, 4 groups of RCA inputs can be freely selected. Exquisite appearance and perfect design: the right size looks cool and attractive, vintage and warm VU meters and tubes can decorate your desk, powerful performance brings wonderful auditory and visual pleasure, very suitable for audiophiles who pursue HiFi music to rejuvenate their amplifiers, active speakers and headphones etc. Warm tips 1. All outputs (2 groups of RCA and 3.5mm headphone jack) can be output at the same time. 2. Standard Soviet Union 6H3N tube, can be replaced by Beijing 6N3 / Soviet Union 6H3N-E etc. Package includes: 1*Tube preamp 1*Power adapter EU plug head not included, you need to buy it yourself