It’s a bit of everything. It’s not the power requirement itself. It’s being able to plug it in, and know it’s behaving as a well powered headphone at its peak. The Sundara was the first headphone I heard that really seemed to work better with more power. But even before I heard it with said power, it sounded great to me. I didn’t know it wasn’t at its best. Now, I don’t claim those changes are huge, but some of them increased enjoyment. The he6se needs the same care and feeding. And, to this day, I am not sure I heard it at its best, despite half a dozen “powerful enough” amps.
But, more than that, if I were a guy that loved the Arya (gorgeous but not my preference), or possible the lcd-x (which I actively don’t like), I would not like the he6se. It’s basically all wrong for those people. But people rave about it like it’s the best thing ever. I have found sound that, to me, trounces the he6se without any of the shenanigans required to get it. And, so, the he6se lost its luster.
To me, the he6se is worth chasing if you determine that what it provides is your primary sound preference. When I was chasing it, I had much less of an idea of what I liked than I do now. And, still, with another 8 months and many headphones later, I would be hesitant to take up the he6se again.
If you are looking for a secondary sound signature and already have the amps to power it, these are an easy recommendation. Otherwise? Ananda.
FYI: I don’t EQ, and I found the he6se to be great as someone who doesn’t EQ. It was also one of the few headphones that didn’t completely piss me off when using EQ. I still haven’t determined why.