EDIT: I noticed your claim that NOS is impossible in delta sigma dac, this is completly wrong and shows that you have zero understanding about DACs. Its trivial to design delta sigma DAC chip without oversampling, conventional DS DAC chips use oversampling becose they are 5bit, so to get the desired signal to noise ratio they use oversampling but there is nothing preventing anyone from making 16bit delta sigma DAC without oversampling, its just cheaper and simpler to manufacture 5 bit oversampling DAC vs native 16 bit DAC.