Try the audio signal source to add the audio signal to the IC2301 input pin, and the left channel appears normal sound, thus the power amplifier level is no fault. The same way checking step by step, when 28 feet of the audio signal is injected into the IC2001, sound distortion, on the basis of this phenomenon judgment fault in IC2306 op amp block and peripheral parts. Because the left channel distortion occurs when the sound is more than normal, so the negative feedback is not normal. IC2306 9 foot feedback pin, pin 9 pin R2386 open circuit. Normal after replacement.