So you believe in burn in.
Burn-in is real.
The main exception made is that listeners are just getting used to the sound of a can.
Great idea. Excellent possible flaw.
Except I have my cans on a separate solid state amp set up to treat 4 at a time as they burn in and I listen to them out of the box for 30 minutes and then put them on the burn-in circuit for several days. If they come with a case or a box, they stay in that whilst they are treated.
During that time I listen to a different pair of cans, so there is no 'getting used to' anything as I don't listen to the newer hps during the interim.
The change in sound for some hps is very obvious.
You listen to a set list of tunes when you unbox and make notes, you put it into the burn-in circuit and you make new notes listening to the same sources after burn-in. Some hps change. Some do not.
The usual issues are bass becomes tighter, cans with a midrange mid-fi or bass bloom have that lessen or disappear (S500 I hope), some have odd lobing of the FR or soundstage (668b) that 'integrates' over time. So on...
My S500's, 662bs, 681f's and Pro 80's are all in the loop right now.
My current listening is from the 681b's or 668b's. My other IEM's and hps are already burnt in.
Consider the possibility that some people can hear things that you cannot.