qualify what you say mate, when talking about things that are controversial, tell the op that a difference of opinions exists, dont make it out to be like its a well established fact.
granted, 80 ohms is a bit higher then usual for headphones, but beyers are very efficient, and i can use my pair, who are 250 ohms, from my phone and still get pretty loud. its simply not optimal, and wont give you the full potential that your cans are capable of, a simple portable amplifier will give you more than enough power, and as my
personal experience, and popular belief goes - the dt770s scale up very well and the better your amplifier, the better your dt 770s will sound.
talking about "burn in" is just opening up a can of worms. lets just say alot of members believe it is vital, while many others will say its a fairy tail.
some will say that one just needs to get used to a new headphones signature...
when i got my dt 770s, i was underwhelmed aswell. the reviews make them sound like super massive bass monsters, when in fact they are not. however, to quote a different forum member "they are very bass capable".
my advise to you is to get the best amplifier you can afford, and to download an equalizer. right now as im writing this post i have the bass boosted by about 13 db and my ears are vibrating
. when i first discovered the wonders of equalization, i boosted more than 20 db in the bass range and my dt 770s took it like a champ with no issues whatsoever. they can be just as bassy as you want them to be.
also, keep in mind that if the music your listening to has no bass line - no headphone in the world will make any difference.