Product Description: This product is a tube pre-amplifier and needs to be connected to an active speaker or power amplifier. It cannot directly connect speakers and passive speakers, headphones, phono amplifiers, cars. Product name: tube preamplifier Tube: 6K4/6A2/6J3?The tube is disassembled) Power supply: DC12-16V, current 1A or more. Power socket: DC3.5/5.5*2.1 Product support replace tube: 6J1 6J2 6J3 6J4 6J5 6A2 6K4 6K5 6AK5 6AU6 6BA6 6BD6 EF93 6K7 GE5654 etc. Pre-stage magnification: voltage magnification 5 times Pre-stage frequency response: 5HZ-500KHZ Pre-level sensitivity: 3V Audio input: low-level signal input such as mobile phone, CD, computer, TV, MP3, etc. Audio output: connect to power amplifier or active speakers Size: 87*75MM Note: The tube preamp is a class A amplification state.. It is recommended to use shielded wire for the signal wire. Common wires may cause leakage or noise.