Hi Conman - now there's a problem - Sifu is great, but 'Conman' can give troubles on Quuq.
Feel we should reply, as your meter is corroded, so you can't check the Yamaha power amp.
Have noticed that Power amps aren't so much of a problem since crap Chinese front-ends have become the biz.
Making no observations, as they own most of us - Pedalling to Morrison's, again - Chris.