As for listening to them, there was a time way back there was a store that offered a run on any headphone they carried connected to an amp. But they couldn't survive, and blamed Amazon (and probably rightfully so). Headphones are one of those things that are really hard to quantify as everyone...

I paid the extra few bucks and the HE-400's arrived not too long ago. Already got them plugged in and going. Wow....     Next up would probably be upgrading to another DAC amp.

Ok, I'll probably bite on the HE-400 then. I can always upgrade to a new amp if it seems I need to.

I can go up to 500, but that's definitely my hard limit. Thanks for the information. Would my current headphone amp be sufficient for most headphones?

I do currently have a headphone amp: HiFiMan EF2A. Would that work on most quality headphones? And what does it mean by being "quite inefficient?"

No, they don't have to be closed as they won't be used outside my home or in public. If need be, I can always switch to my Beyerdynamics depending on what I want to listen to. But I primarily listen to trance. And what are "fast" headphones?

I currently own a pair of Beyerdynamic DT 770 250 Ohm driven through a HiFiMan EF2A amp and connected to my PC. I do much of my music listening while on my PC. I have no idea why I got a 250 Ohm as the little reading I already did seems to show that impedance really doesn't do anything for...