I have a pair of Audeze LCD-2.1 headphones. They sound great, but I find that they put pressure on my ears when I'm wearing them, even when the music is off (and they aren't even plugged in.)
To explain what I mean: If you fully cover the entrance of your ear canal with a finger, you feel a slight pressure inside your ear -- that's exactly the feeling I get when I put them on. If I cover the headphone vents with my hands while the headphones are on, the effect is even greater. After several hours of listening to music, my ears will sometimes ache.
I don't know if this is related to the fact that there are magnetic drivers, but I've never had an issue with non-planar magnetic headphones, and I've used Sennheiser headphones a lot in the past.
I'm wondering if anyone else has experienced something similar with these kinds of headphones.