Others have already hit on the key points here (lack of price/performance correlation, diminishing returns when they do correlate, etc.), but I'll add my own experience just to highlight how personal these decisions are.
I have some open backs (HD 6XX and Grado SR225e, the latter of which I plan to sell), but background noise is pretty common in my home, so my use case dictates closed backs most of the time. But I've found closed backs under $500 to be kind of dicey, at least the ones that I've tried. I think the Sennheiser HD 569 is pretty terrible (but I do have it), and, while I mostly like my Beyerdynamic DT 770, it can sound kind of boomy/muddy on the low end. To be fair, there are others in that price range and lower that I've read decent things about, but I haven't tried them myself.
At CanJam 2-1/2 years ago I tried all kinds of things and came away impressed with DCA and Audeze. I liked the Stealth, but there was no way I was spending $4000 without a divorce.
The Aeon Noire was decent, too, but $900 was still pushing it... like, a lot. And Audeze? I loved most things of theirs I tried. I apparently like a lot about their "house sound" and, while I do use EQ religiously, I like the idea of a headphone whose sound I can also enjoy stock. But Audeze doesn't exactly make much in the "affordable" range, and the one that really had me interested was the LCD-XC ($1300, or $1800 for the deluxe kit). As much as I loved it, there was no way I could justify spending that much.
Shortly after that, I ended up getting the DCA Aeon RT Closed. $500 also felt like a stretch, but I've gotten what I wanted out of it, and I'm glad I spent the money. I've been mostly happy with it, especially with EQ (which I feel it needs to truly sound great).
But I still had that LCD-XC on my brain. And during Audeze's 2023 Black Friday sale, I managed to snag one (the deluxe kit, too!) for $800. That was an even bigger stretch for me, but Audeze sales are such a rare thing that I couldn't resist. I have no regrets. I love them!
But is the LCD-XC $300 (or $800) better than the Aeon RT? In terms of stock sound, I'd say subjectively yes, at least for me (keeping in mind that my LCD-XC is the 2021 revision which is much better tuned out of the box than prior versions). But with EQ? Honestly I'm not sure. Probably not. I want to say the Audeze has more impactful bass than the Aeon RT no matter what I try to do with EQ, but that's subjective and absolutely
not a hill I'm willing to die on.
My post-CanJam desire for the LCD-XC may still be coloring my perceptions. In any event, I'm keeping both!
Anyway, my point is this: Look at how many things had to line up there that were purely personal, subjective decisions. In terms of objective performance, I know from this site that both of those headphones respond very well to EQ. The LCD-XC stock sound corresponds better
to my personal taste, but that's purely subjective. They had to go on sale at a substantial discount for me to be even tempted, let alone buy; again, subjective (my view of their value
to me). And maybe most important of all, I had a chance to spend some quality time auditioning both. Oh, and I know I'm okay with the weight of the LCD-XC, which is otherwise a negative for that model!
