Most of the time I can’t tell a difference but with orchestra / classical music I can.
Also most of the time I listen to music when I’m in a factory with 75db-80db noise floor so it hardly matters how good headphones and source I’m listening to.
It’s just at home where I can fully enjoy my flacs with HD 650… Not that I bother listening to them too often anyways.
I’ll take good mp3 256kbps master over bad flac master any day though.