First impressions
Holy cow, where do I start? The box is very nice and definitely smells like a new car, which is always a bonus
. When I first put these on, I was worried that I'd have to bend the metal headband because of my big head but I was happily surprised to find that I have perfect clearance. The headphone pad is barely touching the leather headband. These are extremely comfy cans. I also didn't even bother with the cable. I've seen too many complaints about it and I have a V-Moda cable anyway.
They sound amazing. I love bass and these surprised me with their punch. I haven't ever heard a dynamic open headphone with this much bass. I don't think these headphones fall very short from my Q40's in terms of bass quantity and punch, and that's saying something. In fact, they have a very similar sound signature to the Q40's in general. The mids are very present and detailed but the lower mids definitely have an emphasis over the upper mids. The highs are perfect IMO. They aren't sibilant at all and they still have a bit of a sparkle. Right where I want them.
As for comparing them to the HE-400... honestly, they're very different. Most of that has to do with the HE-400 being way more textured and transparent but the X1 seems to have a wider soundstage as well. The bass on the X1 sounds a lot more bloated when doing an A/B with the HE-400. Then again, compared to the HE-400's, everything sounds a tiny bit blurry when doing an A/B. egokun used the term "musical" to describe the X1's and I agree with that 100%. They aren't as fatiguing as the HE-400's in terms of highs but they are more fatiguing in terms of bass. Lucky for me, I'm not fatigued by bass.
Overall though, the downward slope of the X1's frequency response is fairly noticeable, but I'm loving it. I can see these easily becoming my go-to headphones for extended listening around the house. Still though, the HE-400's will be my EDM headphones of choice. The speed and clarity is perfect for it. The X1 sounds much more natural which makes them great for everything else.
I don't think I can recommend either one without knowing what you are looking for in a headphone. I don't think I'm going to sell either one of them because they both are very different and have their own strengths and weaknesses.