The vast majority of reviews of expensive gear that I read and watch conclude that the gear is indeed better than something cheaper, though diminishing returns are real, etc…
Given that people’s preferences vary and that a lot of “advancements” in technology aren’t necessarily backed by settled psychoacoustic science, I don’t believe that everything that’s expensive is actually good. Rather, I suspect that due to a combination between confirmation bias as well as people focusing their effort on formally reviewing stuff they like rather than stuff they don’t, full reviews tend towards the positive.
As a counterweight to that, I’d love to hear (even if just briefly) of people’s disappointments in expensive gear. Let’s keep in mind that we’re talking about subjective opinions here, so if you see someone dislike something that you personally cherish, don’t sweat it, it’s all just opinion!
Ember II Tube Amp - I had for a while convinced myself that it did some good things for my DT 1990 Pro (and maybe it did by rolling off the highs somewhat), but if I try to use it with something like my HD58X, it just sounds veiled and lacking in detail and when I compare directly to my phone (LG V20), the phone comes out as a clear winner.
EDIT - I recognize that the Ember II isn’t the most expensive amp out there, but it’s quite a bit more than my V20 phone or my Atom amp, but despite this it gets a lot less use in my house.