This feels like a rather heated thread and so I am sure that my opinion will rub some the wrong way, but that's fine.
I am not a technician but I have spent a great deal of time and money over the years trying to make my digital as good as I can, and I'm very satisfied with where I am, and have a very high-end analog system to match against my digital (to keep me honest).
Going all the way back to my experimenting with different Macs (Mac G5 Pro vs. others, for example)...a common thread in every single improvement that I heard appears to be related to clean power and associated power isolation from other components' dumping power back into the system. The G5 Pro, in spite of it being a much older Mac, flat out sounded better than newer ones, all other things equal. Much, much forum involvement concluded that different Mac models did indeed sound different to each other, and the best explanation was the power supplies used in each model. Fast forward a decade and there's a Computer Audiophile thread that's now over 500 pages long, much of which is focused on the improvements to be had through both clean(er) power and also reclocking digital signals. Much of it may at first seem silly and even counter-intuitive, but I have experienced positive improvements by much of what is discussed there (not all).
There are no absolutes, so the engineers among us that want to challenge this please do, but a well-designed linear power supply vs. not-clean switching supply for example, anywhere in the system, very often adds SQ improvement. When you hear it, you will know it, and if you don't hear it, you will likely doubt this as proverbial "snake oil." This finding could be for digital signal transmission (switch, USB regenerator, digital-to-digital), or even a DAC. Similarly, I have heard improvements in USB cables and ethernet cables (some). When combining many of these "tweaks," you can absolutely get a lowered noise floor, improved sound stage (both width and depth), often tighter and more realistic bass, and you will find yourself listening to your system at higher volume levels than you did without those tweaks. If you measure the DB with a meter, you will objectively find that you are in fact listening to your music at louder levels (peak) because you CAN and want to to hear all the benefits these "tweaks" can provide, and without the raised noise floor, it really doesn't FEEL louder. It will feel much more relaxed yet dynamic and live at the same time. It will actually be addicting. In the case of digital regenerators, I don't know whether the realized benefits in my system were with reclocking the actual digital signal or due to the removal of electrical noise due to better power to the device and filtering of upstream electrical noise. Likely all. I don't really care if I'm honest--I just care that the sound is improved.
I have begun experimenting with optical network isolation both to my Roon server (a modded Mac Mini) and to my OpticalRendu, and I can say that you should try these applications to isolate electrical noise from your DAC, and listen for yourselves. Send the products back if you don't hear an immediate improvement. I predict it will be immediate for you. I am not pushing any particular products, I'm just telling you that they work, even on top of linear supplies and digital reclockers. It all matters.
If you are clinging to a claimed scientific reason why there's zero chance any of this can improve the sound in your system, unfortunately you're going to miss a lot of opportunity.
