If you want to learn more about classdaudio, notably how it compares to a W4S amp, i suggest you to go on the audiocircle website,tapewrite " classdaudio" then go to the thread "120w.classD amp 175$" ,160 pages of tests and comparisons.
At home, it compares fully to my AYON TRITON II,extreme transparency,black silent background,extremely wide and deep scene,any very small mod of my system immediately audible,no need for a preamp, directly connected to my Weiss DAC2,tuby sound, no lack in high frequencies under the condition of a good choice for interconnects and ls cables ( low capacitance litz, unshielded)
The use of a mains cable made in litz wire instead of the standard one led to a very slight improvement in definition.
This amp is a pure bargain and those who believe this is a kind of compromise or only a good quality on price ratio are not right,this amp is so good that if you come to my home ,yu'll think this is a great named amp which is making music.