Just bought this amp on amazon Yamaha RX-V677 7.2-channel Wi-Fi Network AV Receiver. And I love it. I wanted of course to measure high frequency fields of this amp, mostly wireless emissions.
I was really surprised that the amp did not emit any wifi radiation by default. You see it emits wifi only if you plug the antenna a the back of the amp. That is the beauty of Yamaha amplifiers.
I have seen tests done on Denon amps for example very popular TX-NR626 7.2-Channel amp and they emit radiation all the time. You can of course disable it by going into settings.
I was really surprised that yamaha amps are health friendly especially for people who are concerned with high frequency radiation.
So if you do not plug the small antenna at the back of the amp, the amp will never emit any wifi radiation. It still emit magnetic and electric fields of course, that is why I recommend to keep it as far away from your body as possible especially when you sleep. Learn more on how to protect yourself from radiation in your home