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’m not saying that expensive amps correlate proportionally with audible improvements. Sometimes you are paying more for a fancy chassis and a prestigious brand name.
But not all amps are built the same, nor do they sound the same. Some speakers perform noticeably better with amps that can deliver high current. Some amps are overbuilt with better quality parts that will last a long time. Some amps have huge power reserves offering more dynamic headroom. That can make a difference if you have poor house wiring where you notice your lights dim when someting draws a surge of power.