Today I made tests to the power stage always with a 70 watt incandescent lamp in each feed rail, by injecting a sine wave of 1 kHz and load fantsma the amplify the wave came out clean, good achievement but the bias of the left channel was nails in 230mV are about 35mA but I can not lower the preset has no more travel and if I give it to the other side goes up, the other channel with bias well preset to the minimum with 40mV. It can adjust to 35mA.