We dont listen sine wave function in real life...
Well, if you did, you think your system will refuse to play it? It doesn't know the difference between that sine wave or music, right? So if it screws up sine wave, it reasons that it also screws up music. BTW, I test with many other signals. I already showed you multitone:
If you listen to this signal, it will actually sound like organ music. You see that "bad stuff?" Measurements are telling you that they are stomping on your low level detail.