My MT220 modded is now 24 hours burned in
To get the most out of HD800, I was told that I need to invest significant amount on Dac/Amp since it is quite picky on gears to match with. It is hassle for me since I prefer simple set up.
Which brings me to to two things I do
not believe in...
I have owned around 50 headphones and have never
once experienced burn-in. At least not anything noticeable.
"Matching" headphones with colored equipment (read: paying
more money for a
lower fidelity audio device) is another pet peeve of mine. If others want to, it's their prerogative, but I'm a purist when it comes to that. The only reason people advocate spending more money on colored amps and the like (by the way, for those who do not know, even very affordable amps can have a perfectly neutral frequency response, distortion below the threshold of audibility, output power far beyond the requirements of most headphones, and so on) is because they are compensating for the weaknesses of the headphones.
In the case of the HD 800, the major weakness is excess brightness, sometimes not noticeable, other times painfully obvious. There is a peak at 6 kHz, but it's not that extreme, and it's not the primary cause of the brightness. What actually causes it is the fact that a large chunk of the mid-range is sucked out. (I can prove this with measurements upon request.) Normally, when there are recessed mids, it makes the mids themselves sound recessed, but here, it doesn't do that so much as it creates an imbalance and makes it sound brighter than it should. This is naturally more apparent with recordings that have a lot of treble content. More mellow recordings usually sound fine on the stock HD 800. Nevertheless, it has an artificial tonality (not neutral as so many claim) that many feel the need to deal with via various means. So they use equipment that colors the sound to their liking. At this point, you are not describing the actual sound signature of the headphones anymore. Always remember that.
The
only way to attain an accurate (or at least as precise as is plausible) frequency response is with extensive EQ. A parametric equalizer gives you near-limitless control over the audio spectrum: you can reduce or boost any audible frequency; and by any amount down to a fraction of a decibel; and without spending a penny. Of course, it's not perfect, but still far superior to the alternative that inevitably involves spending money on something that alters the sound to a set configuration and forces you to spend even more money if you wish to alter the sound further; an overpriced EQ apparatus stuck on one setting, as far as I'm concerned. (And in some cases, there's a bonus!: audible distortion.) It's like comparing throwing paint against a wall to composing a masterpiece with a fine-tipped brush.
Now if we're talking about higher-end DACs, then those can be a worthwhile investment in objective terms. But I don't put them in the "fix the problems of your headphones with this snazzy piece of gear!" category.
In conclusion, the HD 800 is not picky; people are picky and often don't understand you can solve a problem for free in a way that is higher fidelity than the paid option.
Here's a good post:
http://www.head-fi.org/t/724199/hd800-being-picky-with-amps-myth/15#post_10660374
My MT220 is now burned more than 15 hours and I am getting to like it more and more. If I do not have either of them and decide to choose one between the two, I might choose MT220 because it sounds a bit more fuller and clarity on mid & high and bass impact almost identical (to me at least 
