'True' audiophile sound does not require $4000 headphones you'll be pleased to know
The margins of improvement are very small and are only worthwhile if their areas of improvement happen to coincide with your hearing/listening biases/strengths. If they don't, an expensive headphone can be just 'meh'.
I have HD 800 and LCD 3F phones yet still delight in my LCD 2 rev 1! I even enjoy my old Grado SR-60s from time to time
Elsewhere on the 'net I understand HD 600s and HD 650s are still great phones very responsive to gear up front.
I am one of those who was horrified at first by pricing of Audez'e's new flagship. I've had a complete change of heart. They have
every right to push the technology as far as they can
and to offer it. The price is the price.
Meantime, we of lesser means can take heart that amazing sound from new technology can be had even without winning a lottery.