I think I wasn’t clear in what I was saying. The job of a DAC is to convert the digital bitstream input into an analog output. All DACs must do that identically or the ones at variance are defective. But that part of the job is incomplete. The signal must then pass through reconstruction filters, then passed through an analog line stage before one can listen.
The reconsruction filter used in a digital to analog converter that eliminates the stair-stepped waveforms created in the digital sampling process and restores frequency, amplitude, and phase of the original signal. The process of digital sampling creates stair-stepped waveforms that resemble square waves (increasingly so at higher frequencies). These waveforms contain the original signal, but also have high frequency noise and harmonics added to it. The reconstruction filter – which is basically a low pass filter – removes all of the high frequency signal above the Nyquist frequency that was induced because of the sampling process, leaving a “smooth” sinusoidal type waveform resembling the signal that was originally sampled.
lAnd it is in those stages that the differences in sound quality originate, not in the DAC stage itself. It is our tendency to group those stages and refer to it as the DAC. The difference is not just semantic, rather it enables us to focus the discussion on those areas that actually can impact sound quality.
https://support.auralic.com/hc/en-us/articles/206806457-What-s-the-Difference-Between-PCM-and-DSD#:~:text=A%20reconstruction%20filter%20is%20typically%20used%20in,are%20normally%20used%20in%20PCM%20encoding%20systems.&text=The%20dynamic%20range%20of%20DSD%20decreases%20quickly,rising%20noise%20floor%20just%20above%2020%20kHz.