Beyerdynamic's DT770-990 serie was designed 30 years ago with durable design, in which user can replace all parts easily with couple basic tools.
Fair month ago when replacing pads opened my five years old DT990 all the way to driver to check diaphragm for pieces of hair.
Whole ear cup has literally only one part (besides ear pad) to remove for getting part holding driver out from cup.
While having faster to replace ear pads AKG is definitely less user friendly for any maintenance beyond that:
http://cloud.akg.com/9352/k612pro_k712pro_service.pdf
DAC (D/A converter) is just fashion name for selling less features as more.
Sound cards have lots of other features besides just of DAC.
Also every output has some kind amplifier in it because DAC itself can't drive any load.
While harder decades ago with modern ICs and opamps it doesn't take special parts to make headphone output good for most headphones:
http://www.tomshardware.com/reviews/high-end-pc-audio,3733-19.html
Though there are very real electric engineering reasons for some headphones not being good for all outputs and vice versa.
Like high output impedance which can mess frequency response and wreck damping factor of low impedance headphones.
Or output simply having too low operating voltage (like in battery powered device) to have adequate volume.
But even integrated Realteks output enough voltage for getting to hearing dangerous sound pressure with 250 ohm Beyers.
Because impedance doesn't tell about how much power is needed per dB and Beyers are average in that.
But headphone gaming is about lot more than just converting stereo signal to analog form and driving headphones.
Because human has only two "mics/receivers" it's possible to have 3D sound with just two channels.
In real world such 3D sound can be recorded by simply having microphones in "dummy" head. (or special mics which are worn like IEMs)
That records time delays and other changes in sound signal when sound waves travel to ears.
Then you just need good headphones to have very nice real world like immersion:
http://berkeleybside.com/sound-dimensions-of-binaural-recording/
https://www.youtube.com/watch?v=xpNtNCqP94g
https://www.youtube.com/watch?v=epf1QxuHJv8
We can't put dummy head with mics into game, so in those binaural sound needs to be simulated mathematically from surround/5.1 sound produced by game.
But with actually good headphones it gives very good sense of direction and even depth/distance.
Realteks lack proper binaural simulation and fashion DACs have even less being only two channel stereo devices.
https://www.youtube.com/watch?v=d1_20T8x_OI
https://www.youtube.com/watch?v=B8xZp0WPwxs
https://www.youtube.com/watch?v=wHhwUT4BYMk
https://www.youtube.com/watch?v=8iA0_6ZvhFo
https://www.youtube.com/watch?v=DGwvDmUwFcg
Binaural sound just has very specific and lot harder requirements than any stereo music.
So average headphones aren't very good for it and especially closed headphones have huge challenges in soundstage.
Typical cheap closed headphones are especially bad.
And headphones being open and acknowledged for music doesn't mean them being especially good for gaming.
Binaural sound simply doesn't like any "smoothed"/rolled off trebles or smaller more intimate soundstage etc.
As example total garbage sound headphones can have very agressive "front row" feel in music with lots of bass.
But with those binaural game vids it feels like you have head in bucket... underwater:
As in having no depth/distance sense with some sounds just being more muffled than others and also directions being vague.
Sound Blaster Z has very good features for its price and would work well with 250ohm Beyers insensitive to output impedance.
https://www.overclockers.co.uk/search?ssearch=sound+blaster+z
while fidelios with their fashionable very low impedance would suffer decrease in damping factor.
akgs would fare better.
above that there's newer sound blasterx ae-5 with top level dac chip and about the best headphone output of sound cards with very low output impedance.
https://www.overclockers.co.uk/crea...-5-black-rgb-gaming-sound-card-sc-104-cl.html