I wanted the bass to come. But it never did and hence I got rid of them.

The bass still sucks, IMO.
Rather what did improve -- should've been more specific earlier -- was a REDUCTION of hardness or glare or "un-refinedness".

BTW: And be honest: Do you folks who are critical of some of the observations in my (this) post, or of burn-in "changes" in general, REALLY think we are imagining it all? I.e., it's some sort of psycho- or psycho-somatic phenomenon like confabulation or cognitive dissonance?
Or could some of us claiming that diffs. exists pre/pro-burning have sensitive mental/brain/auditory ckts that pick up a bit better. E.g., like the blind dude in movie Contact that could discern signal from noise?

Speaking of Contact, I must also concede via Jodi Foster's final lines from the film:

Michael Kitz: Please answer the question, doctor.
Ellie Arroway: Is it possible that it didn't happen? Yes. As a scientist, I must concede that, I must volunteer that.
Michael Kitz: Wait a minute, let me get this straight. You admit that you have absolutely no physical evidence to back up your story.
Ellie Arroway: Yes.
Michael Kitz: You admit that you very well may have hallucinated this whole thing.
Ellie Arroway: Yes.
Michael Kitz: You admit that if you were in our position, you would respond with exactly the same degree of incredulity and skepticism!
Ellie Arroway: Yes!

http://www.imdb.com/title/tt0118884/quotes

Ah. OK. I never had an issue with hardness for glare on the K701.

The burn-in thing just doesn't seem like a big deal to me because in my own experience, I have easily heard more significant differences from unit-to-unit, especially for those headphones with more significant production variances. Of course some of these variances are quite significant (beyond measurement error) when actually measured.

The other thing is that a if transducer is supposed to be optimal after X hours of use, wouldn't a manufacturer state so or already do so? I've heard people say their LCD-X sound better after burn in, but I also know that Audeze burns-in their headphones in for a couple of days for QC purposes. Finally why does "burn-in" (in quotes) always result in better or improved sound? Why does no one (or very few) ever say "Burn-in screwed up my headphones. They sound harsher and with less bass!"

So there's quite a few logical and practical inconsistencies going on. The fact that "burn-in" almost always results in better quality sound makes me wonder if the effects are not of a person acclimatizing to headphones' sound signature. In my book, any significant changes that take affect after a short (8-24 hours) burn-in period  = defect. That's how pro-audio treats it.

To sum it up, I pretty much don't worry or think about it, unless it's going to make DT1350s sound like Omega IIs. Then I'll burn it in for 2000 hours. But burn-in for me works like this: "Feel like TH900s tonight. Ah crap, need to prepare myself for U-shaped response." or "Gonna hit the Jades, gonna sound thin with tough treble for a few minutes until I adjust." A lot of it is being cognizant.

I think it bears repeating that a large majority of headphones have much larger problems than what burn in is supposed to "fix", so the objective community in general concentrates on things like driver consistency and distortion, and punching treble peaks in the face.

From personal experience, I've noticed that changing components in the chain like your source or amplifier will have much bigger effects on the sound of the headphone. Even changing the positioning of the cup on your head, or the material of the pads will have more effect than "burn in". This is why I don't reply to burn in discussions on most forums. Sorry for the not-very-useful reply, OP.

like you can see colours vividly

Or some (few) human females can SEE hues (color PHASE) via four cones (like certain birds).
http://en.wikipedia.org/wiki/Tetrachromacy
For HUMANS, this took a VERY long time to scientifically prove. A recent DISCOVER mag article elucidates:
http://discovermagazine.com/2012/jul-aug/06-humans-with-super-human-vision/
Auditory perception is more ancient (=evolved) and much more subtle than vision. So who effin' knows how many subtleties there are? Also, human tetrachromacy has been suspected for decades, but (as noted in the URLs), only recently been validated.
On a pure meta level ... How many more IMPORTANT, SUBJECTIVE SENSORY CUES are to be similarly ... uh ... "discovered".
What we'll get in the meantime is a lotta young, out-of-diaper whipper-snappers, who wave the objective-flag ... who, ya know, think that if they have Twitter, Wiki, and a MODERN education --maybe even w/some elite-univ. post-doc work thrown in -- that they know it all.
Guess what, pilgrim ... or is it cowboy?

ujamerstand: In my neck of the woods, they've CORRECTLY shortened the spelling to the more phonetically-correct "COLORS". Effin' COLORS

Refs:
http://www.journalofvision.org/content/12/1/18.full

The other thing is that if transducer is supposed to be optimal after X hours of use, wouldn't a manufacturer state so or already do so?

A few (notably loudspeaker manufs.) do in their manuals. [Ok ... now how many of you feel the same remarks about burn-in are (are not) applicable to loudspeakers?]

IAC, for cans, I've asked this very same question on various forum/blogs  -- along with "Why didn't the manuf. ( even high-end audiophile, for Golden-Ears-only manufs) don't pre-burn  their devices? And why does Stereophile, TAS, etc., almost always note burn-in times in their reviews?
( http://www.stereophile.com/headphones/806akg/ )
To cut to the chase: no meaningful reply resulted. Surprise, surprise. But then again, look at this thread ... 2 pages and nothing but controversy. [Ah... Socrates is in his element... again!]
IAC ...
Some objectivists have SPECULATED that this (practice of burning in) is way to get you (buyer) to hold on to the purchased device long enough to get attached to it (so won't return it). Also, throw in some of that hobbyists psychology: burning in is a fun, interactive thing to do  (as if one needed more  multitasking in the age of Twitter?) So the fun/interactivity --  be it burning-in or polishing the real-Rosewood grain on those $$ Wilson speakers -- increases the product's dollar value. The perpetuation of these "market designs" are by no mean a cabal. But it does raise a lot of questions.
[BTW: why do I -- who actually, religiously believes in the POWER and MAJESTY of burning-in  -- have to make stronger con-burn-in argument than any of you whipper-snapper-non-believers? Straw-man? Yeah, right?]