The “law of diminishing returns” remains as big a bitch as it ever was. Maybe more so, as what constitutes baseline performance has steadily advanced and there is progressively less and less potential for improvement.
I would defy most non-experienced/practiced/trained listeners to tell an original Modi MB and an original Bifrost MB apart in blind A/B/X testing - let alone do so reliably. And that’s just at the $250 to $600 level - with two DACs that have notable and obvious differences in their technical execution.
Hell, it took me hours of sighted listening and comparisons with both units, taking copious notes, and covering a ton of music, in an otherwise much more resolving chain than they’d typically ever be paired with, to be able to do it, and that was with a good idea of what to listen for and copious experience doing just that.
It was a similar case, initially at least, when comparing M-Scaler -> DAVE to just DAVE (which is easy, since there’s a “bypass” option on the M-Scaler). And that M-Scaler, depending on which version you opt for, can cost more than the DAC it feeds … even though the difference is, from my perspective, last 5% (or less). It’s an important 5%, when it comes down to it. But we were already “most of the way there” with stuff vastly less expensive.
This is not to say that there aren’t differences further up the spectrum. It’s also not to say that the more expensive stuff is better, audibly or measurably than (MUCH) cheaper gear. I’ve run into that plenty of times … and with some extreme price multipliers involved.
With turntables, I think the changes are a lot more susceptible changes. Just adjusting the tracking force makes immediately, and clearly, audible (and measurable) changes in the resultant sound, and that’s without changing any components. Platter speed (or speed-consistency) is another one.