Yes that’s why the video said some ESS (older chip?) dac noise floor was -135 dB. I was wondering what it was on newer ESS chips and also recent AKM dac chips - not finding this in spec sheets.
People who ask a question like this probably cannot hear their DAC's
analog noise floor. If they can hear it there is no need to ask.
Here are some files:
original
Original 8-bit file at near 0dBFS (loud)
8-bit fade
Volume fade saved as 8-bit
16-bit fade
Volume fade saved as 16-bit
Now the noise is clearly audible.
None of the DAC measured here has 135dB DNR when using a -60dBFS input even in 2019, so ESS's measurement parameter/standard is probably different from the one that ASR uses.
[EDIT]
Every 24 or 32-bit DAC add zeros to the lower bits, otherwise volume will be different when playing audio data with different bit depths. Just like when you send a 1080p signal to a 4k TV, it will be scaled to full screen instead of showing the picture at a corner with 1/4 size. In the case of audio doing so would be disastrous because 24-bit data would be 48dB louder than 16-bit data.
Therefore apart from some typos and imprecise numbers, that ESS presentation is only describing a typical PCM digital volume control. There are block diagrams in some product datasheets showing where the volume control is located, for example:
https://statics.cirrus.com/pubs/proDatasheet/CS4392_PP3.pdf
https://statics.cirrus.com/pubs/proDatasheet/WM8740_v4.4.pdf