Hey guys, I'm new here even though I've been lurking for years. I recently purchased the HE-400's from Justin @ Head-Amp and have now had a few days to get used to them.I absolutely LOVE them. I came from Shure SRH440's, so the step up was pretty drastic. I spent months reading threads here on headphones under $500 and finally settled on the HiFiMan's, and I'm extremely glad I did. My biggest contender was the HD600, which I plan to buy later anyway.
The one thing I noticed right away was that despite what others have said, I don't believe these are an ideal purchase if you don't plan on amplifying them. I first ran mine on my iPod and felt a bit uneasy because it was nothing like I had expected. The volume struggled tremendously, so I plugged up my E11 and experienced a whole different set of headphones. They really started to feel like I had purchased worthy phones. It wasn't until later that night when I randomly decided to plug them in to my Pioneer receiver and turn on Pandora that I experienced what these cans can actually do. They awoke like a sleeping giant. They were no longer docile with my ears and screamed with perfection (to me) no matter how high I cranked them. I think I finally settled on 58-60 on my knob as the ideal listening level, despite them still sounding awesome at 70.
So while I'm just a beginner in this very complex world of audio equipment and my judgement should be taken with a grain of salt, I just wanted to clear that up from a beginners viewpoint. These are AWESOME headphones for the price, but you should plan to amplify them! The upside is that it's apparent that you don't have to spend a thousand dollars on an amp/dac setup to really push these -- which is great.
I plan on ordering the Magni/Modi next. After hearing these on my receiver, I can no longer settle with my soundcard + E11 :P
PS. For anyone who hasn't ordered yet, Justin @ Head-Amp was awesome to buy from. He shipped my headphones out the same day, and had them at my door 3 days later. His price was great too (free s&h and free velour pads)