I'll make a list of all the headphones that I'd ultimately would like to include in order to make evaluation list even more complete. At this time, I'm taking a break both from the writing and the spending:) But I'd ultimately like to include the following headphones/earphones
I was guessing you didn't get a chance to hear these. Some people say they are voiced like the Stax 007's so I guess you can imagine the 007's sound sig combined with the HE-500. It excites me very much that you chose the HE-500 as your top value pick, because I feel the HE-400 is one of the best values out there.
You might still put the 500s on top for their more neutral presentation, but the 400s still give you that hifiman sound only darker with extended highs and lows. Your 650 review is flawless and I agree that ultimately it's lack of treble extension is it's down fall (which is where the 400 excels!)
I think it's safe to say you would put the 400's in your value top 5.