Dual op amp: NT1906BNote: The price is for one piece NT1906's open-loop gain: about 68dB (2500 times the open-loop gain) transient distortion (the main source of harsh sound) is much better than the 100+dB chip;The sound performance is very perfect, delicate, transparent, high separation, deep bass, thick midrange, sweet treble...Maximum power supply voltage: +-18V;Maximum offset voltage: +-17mV;Distortion rate: <=0.01%;Bandwidth: 535KHz (when magnification=10)Maximum output current: +-45mA;Transistor: 5 pairs of customized twin transistors;