... circuit system, comprehensive, safe, reliable, accurate, such as short-circuit protection, overload protection, DC protection and overheating protection etc ... 300KHZ switch frequency make this product in high quality. D, Amplifier makes in modular construction. Very low internal friction ... 0.2dbInput inpedanceRated power ,1khz 20 k ohm(W×D×H)mm485mm×46mm×47mmDamping factor overAt 100HZ/1khz 8Ω>900Signal ...