Comparing a Yamaha s301bl to a rega elicit mk5 - a/b on some paradigm 800fs and they sound the exact same. Looking at the specs it makes sense - I don’t know why I’d ever use the full wattage of even the Yamaha without getting hearing damage and the THD being 0.019% vs 0.004% makes no functional difference. Are high end amps the new snake oil? What exactly are you getting for 10x the price here (besides the rega having less features and the rega brand name?)
Here’s an interesting read: https://www.worldradiohistory.com/Archive-All-Audio/Archive-HiFI-Stereo/80s/HiFi-Stereo-Review-1987-01.pdf (Starting on page 80)
It suggests that there’s almost no audible difference between amps which I believe is mostly the truth. Not saying there’s no difference but more often than not the difference is either so small it doesn’t really make a difference or the difference is simply in the imagination of the listener.