i would say nothing stops it from being audibly transparent....
That said, I’ve never heard 2 DACs that sound the same (good or bad, cheap or expensive). I will add (controversially, I know) that the DACs that sound the most alike are the boring-as-cardboard ones that seem to exist at every price point. So it seems to me that DACs that fall short of sounding “real”, “musical”, “awesome” (take your pick) all seem to fall short in the same way or a very similar way. Which I suspect, is likely because they were being benchmarked by measurements alone or primarily (and with the same measurement criteria available to everyone).
It seems that getting beyond that predictable sound (which is achieved by few DACs and fewer still that actually do it well without distortions that become fatiguing over time) is a bit of an engineering art form.
Most $500 DACs fail the test, most $5000 DACs fail the test, and some $50k DACs fail too. So it would not surprise me at all that a $500 DAC could outperform a $5k DAC. But this does not prove the point you are trying to prove... and in making the point you are showing a tin ear to the real progress being made in digital, exemplified by a few examples of excellent engineering that are getting past basic benchmarks to achieve remarkable results. Feel free to stick to your guns on this, but the alternative is to go and listen to a few of the products that are being highlighted as truly superlative (which admittedly are hard to identify in the ‘everything-is-amazing’ audio press) and see if you can’t hear something fresh and new on the digital audio landscape.
either way, enjoy the music most of all.