The board is only a single-channel power amplifier board, if you need dual-channel, please buy two. The circuit design uses A970/C2240 high withstand voltage audio pair tube double differential circuit and A1145/C2705 for voltage amplification. Promote the use of medium power pair tube A1837/C4793, and the output stage uses A1943/C5200 high power for tube. The power supply range is wide, DC positive or negative 20V-90V can be used, as long as enough power is supplied to easily reach 800W, the sound quality is good, the driving force is very strong, and the 15-inch speaker is pushed, there is no pressure! Power supply: dual voltage, DC plus or minus 20-90V. speaker protection power 12V (AC, DC) input. Colour:As shown Material:Metal+PCB Size:250 x 80 x 46mm Package Contents: 2 x Mono Channel Amplifier Board 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.