In article ,
"Morgans" wrote:

The Yamaha is supposed to have pulse width modulation, which if it is fast
enough, can come pretty close to sine wave, I guess.

Powerwise, yes.
As a sinewave arcs up to a peak then arcs down, the pulse widths become
progressively wider then narrower. The average of the area under the
curve approaches the power of of the sinewaveform. A simplified
approximation...
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