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Resolution and Accuracy are terms that are often interchanged when the performance of
an ADC is discussed. It is important to note that Resolution does not imply Accuracy nor
does Accuracy imply Resolution.
The resolution of ADC is determined by the number of bits it uses to digitize an input
signal. For a 16-bit device the total voltage range is represented by 216 (65536) discrete
digital values or output codes. Therefore the absolute minimum level that a system can
measure is represented by 1 bit or 1/65536th of the ADC voltage range.
The accuracy of the A/D converter determines how close the actual digital output is to the
theoretically expected digital output for a given analog input. In other words, the
accuracy of the converter determines how many bits in the digital output code represent
useful information about the input signal.
As explained earlier, for a 16-bit ADC resolution the actual accuracy may be much less
than the resolution because of internal or external error sources. So for example a given
16-bit ADC may only provide 12 bits of accuracy. In this case, the 4 LSb’s (Least
Significant Bit) represent random noise produced in the ADC.
There are DACs with 24 bit precision. As in can a signal be adjusted by the least significant digital accurately. Can I raise and lower the volume at the output by 1/16,777,215 th. of full scale. Yes, that can be done. Can they output the 4 LSB's, yes they can, I've already shown you that, and the other link on the RME shows you that. Will that output be swamped in noise? Yes, but that is due to inherent noise in the analog side of things which cannot be avoided. The DAC itself is doing the job it should. As for 16 bits, if a DAC can't do better than 12 bits accuracy it is a lousy DAC these days. All those you linked over at SBAF are ladder DACs. Lousy DACs. Guess why delta sigma replaced ladder DACs? Because of those problems with LSBs in ladder DACs.
I'm beginning to agree with SIY here. You obviously don't understand this, but also refuse to listen. You've put all kinds of objections that DACs can't do this or can't do that. When they can, you just weren't aware of it. What knowledge or experience has you so dead certain that most DACs are inaccurate and can't do what it is they are supposed to do?
And what is the thing with wanting them to do it at 40 khz? You just moved the target because you think it is more difficult to accomplish. It isn't despite what you think.