Well, the HE-500 has been around longer and it's always been about twice the price, while the HE-400 is one of the first 'efficient' open planars to come under $500. I personally don't mind applying EQ to fine tune for my own unique preferences...it's almost expected. The HE-400 is a great headphone for it's target audience and one of the best in it's price range, no doubt. It's flaws to some may be benefits to others - it's all in the tuning, and it was purposefully made that way. Had it not been for their more accessible price, I would probably not know the joys that planar technology has to offer. Like anything, you will always wonder about the alternatives. Think of it as a quest for what is best sounding to you. For now, the HE-400 makes me very happy, but I am also very eager to try out the HE-500, LCD-2, Mad Dogs and a bunch more that have caught my attention. Who knows, maybe I'll prefer one of their sound signatures more, but only until I try them will I know for sure. This is why I can't wait for the local meetup here in May...I think I'll know what I'm really after once I've had the chance to demo some other options. Still, the HE-400 deserves all the praise it has gotten thus far and it does stand above most cans for several reasons...which is why I originally upped my budget and chose them! If my budget has to change again, so be it...this hobby, like most others, is about finding what works best for you and sharing your opinion with the community.
Couldn't agree more with both of you.
For so many people the HE400 is just a step in the right direction, and for some it is enough. Since the HE400 responds well to eq-ing, and isn't a mobile headphone at all I don't mind its 'fun' signature. But having a near perfect headphone straight out of the box is worth a lot too.
I think the HE400 gave me a taste of what headphones can offer an audiophile, but I can also recognize its shortcomings. But I'm very curious to what the future of headphones has to offer. I don't think I'll buy the HE500, unless its secondhanded, since I already own the HE400 and it is very similar. But I'm hoping for another bang-for-buck headphone in a year that will obliterate the HE400!