I believe it's to do with internal switching clock speeds for class D, or something like that. Cheaper class D amps don't operate as fast therefore it adversely affects the clarity of the high end. The lower end frequencies are less affected. One would assume the more expensive amps like the Mc2, linear research, powersoft etc just do it faster so offer better clarity up there. Whether even those can match the quality of a mid ranged AB hifi amp I don't know.
I had seen those when looking at possible class AB amps. Doesnt look like they have adjustable limiters though, which I do want.
