a convincing soundstage comes from multiple cues telling the brain the same thing. what makes a soundstage to crumble is when some cues contradict each others. with headphones the simple lack of head tracking is enough for some people to never experience more than a line of sound between the ears. that is solved by the A16.
for some the signature is just too far off from how our own HRTF impacts sounds in our daily life. the A16 will try to deal with that, and I suspect that placing the little microphones in the ear correctly will be just as if not more important than the headphone used. but both can limit the final result. obviously headphones might end up having 20 or 30dB differences between their signature and what our ears get with the speaker in a given position at a given frequency. can the headphone+amp handle that much of a change? attenuation is child play, but boost is another matter obviously.
I'm guessing that when some EQ goes really crazy, the Smyth family might decide to set up a limit instead. same if a headphone's FR is only made of spikes, the compensation might not bother correcting everything to the last dB(or the result might just suck bad because of way too much EQ and ringing from it).
but something like a hd600 is not a nightmare when it comes signature. it's also very fine when it comes to distortions(only the low end sucks a little but low freqs don't matter for direction cues). so I'm expecting fairly convincing results from such a headphone. the native perception of soundstage is IMO irrelevant for what will be done to the signal. the hd800 is a good candidate because it is light, comfy for most, and measures real good for most variables really. of course high fidelity is always the better option when it comes to making a copy of something so it's a good candidate. but don't think that's because the hd800 feels wider on it's own, it's not going to push a speaker 3 meters further. if it did that, it would be bad simulation ^_^.
what I would stay away from are headphones with stupidly weird frequency responses, and those with really high distortion levels or known ringing issues(as in audible) at some frequencies. for the rest it should be fine most of the time. I believe most headphone purchase decisions will come from actual experience, and from the simple idea that such an expensive device deserves an expensive headphone. I personally don't like that idea because it's the same idea that leads to 500$ cables and "audiophile" fuses for the house. but it's still true that headphones and speakers are usually the weak link in a playback system. so there is nothing wrong with people who wish to improve on it. not only because they do what they like
, but also because it makes sense.
that said, unless there is an obvious and massive problem, I'm going to stick to my hd650. because I can wear it for hours and that's really the only reason I have it. not very hi-fi of me, I know, but that's how I roll most of the time. I like nice and cozy more than I like uber fidelity and glorious numbers. but that's me, it's not a rule and it most certainly doesn't define right from wrong ^_^.
