Which it's artifacts are, even the non technical can see it in any Class-D's 1 or 10khz square wave from on the amps outputs, and in the phase shift the filter produces down to 4khz in many cases.You can't see switching noise on any frequency a class D amp can amplify. All that can be seen is a sine wave known as the 'residual'. You've been told this before. That sine wave is at the switching frequency of the amplifier; if you are saying you can hear 250KHz or 1.2MHz sine wave good luck trying convince anyone that you aren't a nutbag.
Regarding phase shift, filters in most class amps are set to 60-80KHz and are usually 12dB per octave; phase shift thus derived is less that you would see with a 6dB slope (with a 6dB slope phase shift can be seen down to about 1/10th the cutoff frequency). So the 4KHz thing in the statement above is just plain false. You might see something at 20KHz though, but it would be slight even on an older class D amp.
I know your [sic] bringing out your own Class-D amps just like Ricevs is also using off the shelf boards (maybe slightly modded) that's maybe why the negatives toward the GaN Technology, that now even Texas Instruments are behind.We have our own circuit and are not using anyone's boards. We filed for our patent over a year ago and expect the patent soon.