Not surprising for a class D amp.
kosst, I think it’s linear, but still just looking under it’s skirt, the Vidar gets my nod by a long way.
STA-200 https://www.audiosciencereview.com/forum/index.php?attachments/nuforce03-jpg.17070/
Vidar https://www.schiit.com/public/upload/general/vidar-internal-1920.jpg