I just got my HE-400 and I gotta say, these are probably the most sibilant cans I've ever listened to. Ear piercing highs... Every song I've tried (flac/320, various different artists and recordings, etc.) that has a lyric with the letter "s" in it, it's ear piercing. Cymbals aren't quite as bad but still painful. I've tried a lot of EQ in foobar to reduce the highs but I can't seem to get rid of the sibilance without losing the highs all together... and volume definitely isn't the issue
I'm hoping someone has a really really good plan for me?? It seems most people have zero issues in this category :(
As you can see, my first impression of the highs wasn't great either. Once I let my brain burn into the sound, and settled at a -3dB at 8kHz and -3dB at 16kHz EQ, these headphones win my vote by a landslide. In fact, today I shipped off my X1's because the detail and speed of these is unmatched (compared to the headphones I've listened to ). Even though the X1's have the optimal frequency response for my liking, I can easily achieve a similar FR without losing any detail with the HE-400.
Still sad to see the X1's go though...