Not even slightly.? The filters are resonant, meaning that they both reduce harmonics and boost the fundamental. You could consider that the filters take the energy off the edges off the square wave and add it to the center of the waveform to boost the middle to make a sinewave of greater peak amplitude than the original square wave. There's no way you'll get thirty-odd volts peak to peak from a 12 volt supply without a resonant filter circuit, and I don't even want to think about the splatter of harmonics all the way up to daylight that you'll be emitting. If you want to measure the initial drive to the LPFs, you could measure the waveform at the drains of the output transistors, but leave the LPF in circuit if you're connecting anything to the output, even a dummy load.
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Julian, N4JO.
Julian N4JO