Just an update guys. After burning these in for a couple of days, the difference is astonishing. Signature went from following an extreme V shape to an almost neutral shape. Previously, I could not hear vocals at low volume as it was all bass and highs, but now vocals are strong in the whole signature. I think it's still not good enough. The sound is not full and seems rather thin but you can at least listen to them now. They're probably now at least equal to any cheapo headphone but hopefully, this will get better over the next few days. But seriously guys you won't believe the gigantic difference.
Please point me to any idiot who says burning in is useless. The difference is JAW DROPPING and I am now interested in finding out the mechanics behind it, it seems that such a difference in sound should only be caused by actual mechanical manipulation. How could playing these for an extended time on some burn in tracks achieve this difference is beyond my comprehension to be honest.w
Edit: Haha yes it's on stereo guys, I am not that dull.
Edit 2: I used to have to crank up the 250 hz frequency range just to make these slightly listenable and it wouldn't give that much stronger vocals as they were already extremely weak and maybe non-existent but it made them better. After the burn in, WOW the mids are strong maybe too strong. I got the cranked up 250 hz back to neutral and oh boy the mids sounded just perfect. This is the most objective evidence to me. THERE IS A SUBSTANTIAL BURN IN EFFECT IN THE PRODJ100. DON'T THROW THESE AWAY IF THEY DON'T WORK FINE AT FIRST.
I think "burn-in" is a real experience but it is mostly (if not entirely) due to the ears/brain adapting to the new headphone.
Suppose that you would just have put your headphones for a few days in a special drawer that, according to many, makes headphones sound better. So, many people, who don't like the first impression of their headphones, puts them in the drawer for a day or two, and then takes a new fresh listen. And, "Holy cow, you won't believe the difference!" is frequently heard.
The drawer is truly magical because it almost without exception turns the phones to better phones. If the phones were too bassy for the taste of the listener, the bass got tuned down. If they did not have enough bass, the bass was tuned up in the drawer. And so on, for every possible complaint. A truly magical drawer it is!
And furthermore, why won't the manufacturers put their headphones in a special drawer before shipping them to the customers? It would seem like a cheap way to make better headphones. Maybe they tried that but found that it does not work when used at the factory. The special drawer only works its magic when used after the first listen, and it only works for that listener.
If customer A sold his "well burnt-in" phones to customer B, customer B would still benefit from putting them into a magical drawer for a day or two. Maybe customer A thought that the phones got too much bass, and used a magical drawer to tune it down. Customer B then finds that the phones do not have enough bass, and the magical drawer now tunes the bass up again. How is that possible?
Suppose that the drawer actually does nothing and the whole work of tuning the phones to better match the listener's preferences is done by the ears and brain of the listener. Would not that make more sense? People for some reason find this idea very unintuitive. That is odd because there are people with so much earwax that the frequency response of the ears must be affected, and they won't notice anything because the change was gradual and the ears and brain must have been compensating for it in some way.
I actually thought that there was a high possibility that this "burn-in" thing will be happening to you. You didn't mention your previous headphones by name, so I think that you are relatively new to (good) headphones. You say you enjoy your laptop speakers. They for certain will lack bass, and probably also high frequencies. So they are all about the mids, and that is what your ears and brain are adjusted to when it comes to music listening.
The Koss DJ100 also does, in my opinion, have some unevenness in their high frequencies, that makes the first listen easily a bit disappointing. It seems that for many (ears and brains) it is possible to adjust (to some degree) to that fault.