First, I'm not just making assumptions, I happen to have a PhD degree in electrical engineering. The best known way to use a full-bridge topology is to use a differential balanced input signal. This means that any single-ended signal is first phase-split into two out of phase signals. Each signal gets modulated using one half-bridge leg of the full-bridge topology. The output filter and speaker is connected between the two half-bridge legs of the full-bridge power stage.
So if each half-bridge leg is modulated at a switching frequency of Fs, the full-bridge differential output will have an effective modulation frequency of exactly 2Fs
View attachment 45276View attachment 45277
As you can see in the attached images, not only that the effective switching frequency at the differential output doubles, the number of PWM levels increases from 3 levels to 3 effective levels.
Both doubling the switching frequency and increasing the number of output levels have positive effects on the sound quality, as the harmonic distortion decreases by more than 50%.
Instead of taking a single-ended audio signal and splitting it into differential, the best practice for full-bridge class-d is to feed it with a balanced audio signal, making the full-bridge class-d amp a native and true balanced amplifier
This is exactly how the Iceppwer AS series works. If Amirm could measure and review the Icepower 700AS1 modules, I'll bet that it will outperform even the purifi's 1ET400A , which BTW is also based on a single-ended topology.
Eli