Yamaha M-60 Power Amp Adjustment and Demo

I have a Yamaha M-60 power amp in my second stereo system. It ran into the speaker protection mode recently. I used this opportunity to do a bias adjustment based on MFR's service manual. Also I compare it with my back up unit (Anthem MCA 30) by doing a demo test. The result tells me why I still love my M-60 power amp.