Diminishing returns is entirely subjective when it comes to hobbies, especially anything where the rating of quality is also subjective. There is no agreed object criteria for “good” in audio. Some say clarity of signal is the gold standard, others value classy coloring of a sound. Some value build quality, others value a fancy looking headphone. Some value comfort, others value portability. There are a plethora of criteria people could find important. It really depends on what a person values and whether they feel that the extra cost is a worthwhile investment. Most people agree that there are diminishing returns. However, the price point and quality that is being diminished aren’t agreed. Infact it’s even more complex than what I stated. Personally, I’ve spent far more than your typical consumer and have the opinion that diminishing returns hits far UNDER the price point most people expect. Yes, ive spent the money, yes I enjoy my gear, however it’s hard for me to see the thousands of dollars value in the headphones I have vs something like a DT770. I can ceetainlt hear a difference and REALLY enjoy the clarity and soundstage of my headphones. However, i still feel that 90% of what i desired is achieved theough cheaper gear. Not everyone will be the same.
No because mine is class A and would probably live a short hot life.