[Makiah S]

   
A lot of people have been saying DT 990 is a good phone, but should i get a soundcard with it?

yea, chances are the On Board audio you ahve now won't have a strong enough amp. A sound Card would also allow you to get a better DAC as well which would improve sound as well 

 

[Garryfish]

Last question - would i see a big improvement when it comes GameCom 780 vs HD 598 with sound? Because its a 70 dollar headet to a 200 dollar headset.

 

[davidsh]

Only you can answer that question.