why are you irritated if people say they can't tell the difference between the 250 and the 600?
misread your post.
What about people who've heard both and came to the conclusion that they can't tell the difference between the 250 and the 600? are you still irritated then?
during my own research before buying it, i came across varied opinions on whether the 250 and the 600 sounds the same or not, and whether said difference can proven or not, i've never heard the 600, but i've heard the 250 premium and 250 pro. There are varied opinions on that two pairs too, some said 250 pro has better bass and less dry, and more coherent, some said it should sounds the same.
When initially listening to the 250 pro, my expectation bias sets in and i thought the 250 pro sounds better too. A few months down the road somebody lent me a 250 pro and i blind a/b them with my 250 premium, and if i don't pay attention to the feel of the leather pad, i can't reliably tell the difference between the two, they sound the same to me.
maybe some people can't hear the difference between the 250 and the 600, just because experiences are different doesn't mean that one has to be right and the other is wrong.