Construction quality got me. The construction quality of these cans is flimsy and mine just blew up this week. Pretty sure that, but for the circuit protections on my amp, it would have taken out my amp as well. Replaced the Koss with the Hifiman HE6se Ver 2. Did it because I got an open box deal for $600. Great $600 cans, not so great at list price. Still miss the soundstage and airiness of that an electrostatic supplies! If I got another electrostatic, I would try Stax.