Re: For Ascend owners with headphones...
I'm a frequent Head-Fi member and as far as neutrality is concerned you're going to get a thousand different answers. It's really hard to get a headphone to be as neutral as a speaker with the one driver you have to work with. There are a couple of hybrid designs, but not many. With that said, many people feel that the upper end STAX electrostatic models are the pinnacle of clarity and accuracy in a headphone.
Personally, I own an Audeze LCD-2 and Oppo PM-3. I use the LCD-2 at home with my Schiit Bifrost Multibit and Asgard 2 amp and it's incredibly addictive. I would say that the impact and slam of the LCD-2 is incredibly speaker-like, which is what Audeze is going for. They want to nail that and imaging like a stereo system does and they indeed do that. I still feel like the midbass punch is a little less than the towers and the treble is certainly much more recessed. I use my PM-3 primarliy with an iBasso DX80 DAP and it also has an awesome and addictive sound signature, but again, slightly recessed treble that does not have the same kind of detail as a RAAL tweeter.
I think if you really want to replicate the midbass slam and utter treble accuracy of the Sierra speakers, you'd have to have something like an Abyss or other top of the line headphone. Only those uber expensive headphones can nail bass and treble at the same time from what I've seen. All of the planar headphones that I love, even the ones I own, are ruler flat until you hit the mids/lower treble around ~1.5 kHz and then their treble response becomes very irregular and peaky. This is fine for music with me, and even makes a lot of poorly mastered metal a lot easier to swallow, and gives a sort of euphonic signature to a lot of things I listen to, but I can't stand it with movies. I want perfect accuracy when I watch movies, and the ONLY rig I've ever found that does that is my Sierra rig.
-Alex
PS4/Nvidia Shield --> Emotiva XMC-1 --> Emotiva XPA-5 --> Ascend Acoustics Sierra Towers and Horizon Center w/ RAAL tweeters (L/C/R), HTM-200 SE (Surrounds), 2x Rythmik F12 subwoofers