Build Quality is there, how about sound for the price?
Presentation: These feel higher quality than my other cans, and the build is really great for the price. The material is nice, and they are very sexy looking. The grills give off a little glitter reflection from sunlight or artificial light. Cables are good, and thick at end points.
Comfort: Yea its there. Comfortable to wear for hours. Pads are lush and thick. A bit on the heavy side, but super light for planer cans. My only complaint is that the pads can get warm, but if your in a cool room it should help combat heat.
Sound: I'm in the minority it seems here. I'm not impressed by the sound. For the price it's not bad, it's actually good. You get that signature spacious sound form planars which are fun. The sound actually sounds like they are coming from the room, and not the cans themselves. Almost like artificial exterior speakers floating around you. But, the detail, imagery, bass are lacking.
Do I recommend them? No...maybe. These are great for classical music since the instruments sound like they are in the room with you, but at the cost of detail from the instruments. If you already have the HD 6xx or AKG7xx, I would not recommend these since those are superior in almost every way, besides build and signature-sound (spacious). The Sennheiser HD 58x Jubilee at $150 in my opinion are the better buy: offers more detail, bass, easier to drive, and imagery. 3 Stars!
Edit: I added another star and changed title to reflect it. I reevaluated the cost to performance, and due to the price, build and sound quality, I feel the HE-4XX deserves a higher score. 3 to now 4 stars!
Edit part 2 (11/17/18): Wow, these cans just keep getting better the more you feed them. I hooked them up to my Liquid Carbon X + SDAC, and it brought out the true potential of these cans. 4XX needs power, they are a bit hungry. Then days later I received my XLR cable from Periapt, and wow, they scaled even more showing more potential. The 4XX are now my favorite cans, and may now be my favorite tech (planers). Cost-to-performance really shines when fed by a proper amp. 4 stars to now 5!