Return Top Result in Matrix using DAX

Hi AltGr9 
Add the Class_new and Row Header columns to the data table

Class_new = 
SWITCH(
    TRUE(),
    [Class] = "Class 1", "Class A",
    [Class] = "Class 2", "Class B",
    [Class] = "Class 3", "Class C")
---------------------------------------
Row Header = "Top Site"

Follow these steps

Тop Site = 
VAR _maxdate =
    CALCULATE ( MAX ( 'Data'[Amount] ), ALLEXCEPT ( 'Data', 'Data'[Class_new] ) )
RETURN
    CALCULATE (
        MAX ( 'Data'[Site] ),
        FILTER (
            'Data',
            'Data'[Class] = MAX ( 'Data'[Class] )
                && 'Data'[Amount] = _maxdate
        )
    )