Your statement about having the switching freq much greater then the
output freq I agree with. But if you wanted to make an amp for 27MHz...
what switching freq would you have? 2X, 5X, 10X ? Also, with a high
switching rate... with square-waves... you have tremendous harmonic
content. You also would require much higher frequency amplifers...
along with the quantum leap in complexity of combining all those
amplifiers, A/D conversion, etc... I think your idea would work... it's
just not practical in my mind.

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