If there was ever a pair of headphones that deserves first ballot headphone hall of fame status, it's got to be the K240M. I've had a pair for better than 20 years, and they still sound great...and as the cans in my computer rig, they get plenty of use to this day. Amping them has really brought them to a level I'd not thought possible, but they still sounded decent powered by the headphone jack of my old NAD amp.
For years, I saw these cans in use in recording studios, in radio stations, and any place else where it seemed that good, clean, true reproduction of the source signal was critical. Though less common today, they are still very well represented. Those of us who have owned a pair know why.