I think you misinterpreted this. The amp at the link you provided was an older amp that was only switching at 200KHz. Nobody has been building amps with switching speeds that low in a long time, unless its for subwoofers only. Also, we don't know why the risetime is as slow as it appears since the data on the amp itself is lacking. That can be caused by measurement errors, but it can also be caused by analog signal processing before the encoding scheme.So that makes the scan frequency in this example only 200KHz(!),Wrong again when have you seen an amp that can do 200khz, have a slewing audio frequency square wave like this, the sides are collapsing in like the leaning tower of pizza
So its erroneous to apply the results of this nearly 20-year old circuit to newer amps.