I am confident that HE400SE is the best sounding planar at sub-140€ price category and beats many way more expensive products. In fact I was totally amazed how good they sound and feel out of the box. With a tiny bit of EQ these are superb.
Lack of distortion makes HE400SE a delight to listen to. The cups are big as kettles and the cushions soft making these quite comfortable to wear, albeit they're a bit on the heavy side. Another good thing is that unlike many headphones, these can be adjusted for small head aswell. The supplied cord is soft and flexible but not very long.
All in all HE400SE delivers a lot with a little money.