Sennheiser HD 800 S is $1700 and has been around for years. Or the Meze Elite Tungsten at $4,000 - if Apple can get 80/90% of the way there at $549, they'd be a steal for the right customer.
The quality x price curve is not linear. Expensive materials and engineering often produce only incremental quality improvements, if any. Sometimes the improvements are only cosmetic. So Apple's headphones would need to be a lot closer to the best of the best than 80-90% in order to justify their price.
The feature that applies a hearing test as an equalizer setting make the APM sound pretty damn good, so much so it ended my 20 year long headphone-collecting hobby.
Before hearing-tuned EQ became a thing, trying headphones was like trying food. No matter what someone else said it was no guarantee you'd like the sound. Conversely, you might find a cheap pair that sounded spectacular to you. The APM will sound very good to just about anyone, with the hearing test EQ applied.
I think every headphone maker (or better yet, DAC maker) should have this feature. Audiophiles are often old, a hearing test EQ can make them hear music like they're 20 again, and they'll pay for it.
