@lojay @kothganesh et @Johnjen : great posts.
The HD800 is indeed not the king for mids. When I compared the HD800 and the SR009 that's what I realised: SR009's mids are so "right" . But I wouldn't trade the soundstage for the mids . Matter of tastes I presum and I listen more to instrumental music so vocals are not my priority.
That been said, I've no problem to listen to Youn Sun Nah , James Blake, Newton Faulkner, Dietrich Fischer Dieskau or even Norah Jones for example.
BTW I can confirm that the choice of DAC and amp is really important. I listen much more vocals since I have my Metrum Octave for example. I didn't notice this fact during the first month but after the read of Purrin's review of the Octave I realized that the strong point of this R2R dac is mids and I realized that I've changed my habits and I've started to listen to lot more vocals.
I heard my HD800/Sonett 2 and a SR009/EC Electra side by side during an hour at home, with my music in a perfectly quiet environnement. The SR009 is definitely more neutral and faster, has more mids and better mids. Overally , IMO the SR009 is closer to what we could call the top notch fidelity and accuracy. so SR009 wins ... but not by a large margin IMO. and IMO the HD800 provides more wow effect due to its incredible soundstage , more bodied, energetic and impactful sound. If i should give a metaphor to explain my feelings : The SR009 could be the Old wise man who don't need to impress to tell the truth and the HD800 a kind of slightly more immature and aggressive youngster. Right now I prefer to live with the Youngster. Maybe I'm not old enough myself.
Right now, the three best headphones I've ever heard are the SR009, the Abyss and the HD800. Each one had its pros and cons but neither the 009 nor the Abyss would replace the HD800 in my heart right now. Even if I had the money to purchase them and buid the system accordingly. I don't consider that those headphones are complementary . They are more three different way of seeing a TOTL headphone. e
I haven"t heard the HE-6 yet. I like a lot the HE-4 and the HE-500 so I would be very surprised to not like the big brother . I didn't like the HE-560 at all though ( I couldn't ignore the agressive sibilant treble and the overall fatiguing forwardness of the sound.... Even EC 4-45 an Metrum hex didn't help) ... it was at a meet though so Maybe these impression are completely biased.
For all these headphones, the whole system definitely matters.