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?)
I ran a nice Onkyo RZ (which was their higher end model) surround receiver with my B&W CM9 S3 floorstanders / 5.1 surround setup for years and it was a great reciever, no complaints.
I upgraded to a Rotel rap-1580mkii and it seems to handle the B&Ws better, even at lower volumes. This could be entirely subjective, but it simply seems the extra headroom allows the Rotel to sound more effortless.
What is not subjective is that the Dirac on the Rotel is worlds better than the Onkyo’s room correction solution and the 120W per channel on the Rotel can get far, far louder than the 70W per channel on my old Onkyo without distortion.
Was it worth the $3K price difference? That is of course entirely subjective - for me and my particular setup / use it has been very satisfying. For most people an Onkyo, Yamaha, etc is just fine.