... ) Professional stereo power amplifier with transistor 2) Reliable protective device for short circuit, overload and over heat PL Series Power Amplifier (2U ... are Input Gain, Ground Lift Switch to eliminatehum, Power LEDs, Channel 1 & 2 level, LED's indicator, stereo and bridge modes ... Gain, Ground Lift Switch to eliminate hum.12) Power LEDs, Channel 1 & 2 level, LED's indicator, stereo and bridge modes ...