No, there are also diagnostics for protection mode reasons +++++++, 3 to be exact, Current fault, Thermal, like in shorted spkr wires, and DC, While you are speed reading tell me how you get into those modes ! Have you measured the amplifier output DC voltage of each channel with the unit turned on but volume at minimum? Chances are it would behave normal, that is, very low but imo it is still a good first step.