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?)
A “better” amplifier is not snake oil. However, more expensive doesn’t mean better definitely. With that being said you should be able to see, feel, hear the difference between an extremely cheaply manufactured $350 amp and a $4000 one. I don’t have experience with the Rega in question, but if you don’t notice a difference, then I’d say that’s a detriment to that Rega, and not necessarily other amplifiers.
It’s the same way that buying a Lexus is “snake oil”over a Camry. It’s better engineering, better materials, better build quality. It doesn’t mean it’s faster. It maybe gets there more efficiently, smoother, maybe looks and feels better along the way, and maybe someone took more special care in designing it and building it for you.
If you can’t understand or experience that difference, then enjoy your $350 amp, but know that you are likely missing out on something more special if you’re open to it.
With that said, I’m not comparing the Yamaha to a Camry. It’s honestly further down the list comparatively, but you get my analogy I’m sure.