Hmm...
Thank you for all the replies.
The three headsets I mentioned is priced between $430 to $500.
I can get a mint-conditioned David clark 13.4 for $250 to $280.
All double-corded, I guess people call them general "GA" cords.
If the one with ANR vs. the famous 13.4 differs by about $200,
and if a headset lasts very long time, isn't it better to get a well-built ANR
headset?
I believe A20 is superb but the price is out of range. The only reason I am looking at the X is because the used ones are in a decent price range, yet people claim it is superb (from the review of the new one).
It's very hard to make a bang for the bucks.