I'll take a shot.
The "load" would be on DACs sample rate filter eq at SD sample rates. ie. The fact that said eq is in use at all.
In SD sample rates (especially 44.1k) the sampling frequency is RIGHT next to the audio band. So close that the sampling frequency needs to be eq filtered out with a steep lo pass or it will roll into the audio band. This is in the analog domain after the AD chip. This kind of steep eq is a hard circuit to build! It turns out that the factor you are comparing between different DACs at SD sampling rates is that analog eq circuit.
Meanwhile HD sample rates put the sampling frequency miles away from the audio band. The margin is so wide that eq filtering is not needed. Like tape bias whistle.
Right - as I mentioned previously, due to steep filters for 44.1khz audio there's a
theoretical benefit to e.g. 48khz and beyond, if your DAC is older/lacks configurable filters/has a bad analog stage design, as it gives you more room to do that filtering.
But
- most modern DACs (with commodity chips that measure excellently as a species, better than even the most expensive DACs ever have) are going to implement these filters in exactly the same way, using the same parts - this is why we often see "bespoke" $20k DACs fail at a basic level compared to $200 DACs when put to measurement tests - because well-designed DAC circuits are a commodity, and well-solved. It's the audiophile hobbyists which try to re-solve it that usually implement bad DAC circuits - this is also why many modern DACs let you select the steepness of this filter, if you care to.
- the place where this filtering intersects with the audible band,
if it does at all, is at the very top of the spectrum, well above 16-17khz, which none of us over the age of say 20 or so can hear anymore. So if you happened to have a DAC that wasn't good at this as demonstrated by measurements, the artifacts would be largely or totally inaudible to you, unless you're a heretofore undiscovered freak of nature.
- 48khz gives you plenty of headroom for a reasonable rolloff - so again, samplerates higher than that are capturing ultrasonics which are demonstrably, from the perspective of the human ear, junk data.
If your DAC sounds better at 96k because of this, upsampling SD program is an excellent workaround. The music signal is in there fully. The analog filter eq is your problem. We remove it from the equation. And yes, it's gross compared to any generational loss from upsampling. So much so that it's not fair to mention.
Right, so 96k puts the sampling frequency miles above the audio band. Not sure what anyone thinks they need 192k or above to do. I mentioned my tests. There may be some processing that benefits from extreme HD sample rates (I doubt it). When you're done with that, the full program can be put into 96k with no loss.
Yep - this is why DACs with selectable filters are nice. But again I'm not convinced that there's real data that anyone "needs" 96khz to give them enough filter headroom - there's not going to be audible differences in filter steepness between 48khz and 96khz, because any filter artifacts are gonna be way beyond all of our hearing thresholds.
