It is due to Topping's boasting magical skills.How a 92db SNR chip can deliver 120db SINAD ?
The details are all black boxes, but it seems that it is realized by applying NFB in multiple stages. PA5 adopts the same method.
The magic of NFB can provide excellent numerical data, but it also has a negative side when it comes to sound quality.
A non-NFB amplifier is a completely opposite idea.