The bass is quite good on the FX40s.extension, quantity, balance and just enough impact for realist listening.
33 hours of pink noise, and these phones have mellowed out for sure. highs are still quite crisp but not as painful. cymbals are still a bit of a pain in the eardrum but noticeable difference after this much burn in - if anyone's wondering.
There is actually quite a sound stage as well! it's more wide and shallow. Mids are now pretty present, and in your head, but guitars and drums surround you. Definitely more pleasant, and has me questioning all the other phones on my "to buy" list. speaking of which, i'm going to the mall today to give the sony xba-3 another shot, was quite impressed last time i listened.
It's a little depressing how good the fx40s are, since i'm a little less excited by the xba-3, since i pretty much had my socks blown off when i first tried them.