Always check R121 15 ohms - this one is for grounding to the chassis and can be removed without lifting the board.
under
https://www.circuitbasics.com/design-hi-fi-audio-amplifier-lm3886/#Balancing-the-Input-Bias-Current(go to "Ground Loop Protection Circuit") was in parallel to this resistor a bridge rectifier (actually two diodes).
If the voltage across this resistor goes above 0V65, one of the diode does start to conduct and protect the resistor.
also to find in Bryston amp devices - go to post #9+13 under
https://www.diyaudio.com/community/...olidstate-power-amps-how-to-calculate.213912/is this a good approach ?