benthughes and purpleangle, thanks!!
Funny... I had listened to and much enjoyed the HiFiMAN HE-400s (WITHOUT a pre-amp, incidentally, but with my iPod) when I was considering the Grado PS500s. I'd forgotten them in this consideration, regarding them as higher end than what I was looking for right now, but they are... $300. And I have already tested them (should go back with my portable amp though).
And in my earlier comparisons, they had even more of the features I listed here, which were what my first good headphones (HD 598) introduced me to... big sound stage, great transparency, great comfort. I was not as attuned to assessing bass when I heard them as I am now, so I'm not sure how they compare to the HD 598s in that regard (likely to be more, as the HD 598 are rather weak there).
HE-400s are one of the most frequent headphones of folks on this forum (# 9, with the HD 598 being #7) as reported here... http://www.head-fi.org/t/109756/rank-the-headphones-that-you-own/4065#post_10501387 .
Just for fun, here are rankings of the HE-400 against other most-popular 12 headphones from ( http://www.head-fi.org/t/109756/rank-the-headphones-that-you-own/4095#post_10508731 ) :
To help read... the first person (column) ranked the LCD-2.2 and the HE-500 over the HE-400. Others likewise.
When compared to all 1,000 headphone rankings of the last 5 months on the thread "Rank the Headphones That You Own," the three people who rank both HE-400s and the Fidelio X1 all rank the HE-400 above the X1 (usually by just one place).
There are no rankings of the AKG Q701 against the HE-400 in that set (no one reports having both). Also, there are no rankings of the AKG Q701 against the Fidelio X1. Someone does rank its close mate, the AKG K701, as higher than the HE-400.
Edited by ruthieandjohn - 5/10/14 at 7:31pm