[eric838]

was about to buy the 250 ohms pro ONE but I saw the 600ohms premium one.
 
What is the difference between 250ohm and 600 ohm one?
Should that worth spending extra $150 to get premium one?
 
I'm using Asus xonar essence stx sound card /w built-in headphone amp that could take up to 600 ohms

 

[nihaz]

Have a look at this article/guide, I'm sure you'll learn about the differences here...
 
http://www.head-fi.org/t/513393/guide-sonic-differences-between-dt770-dt990-models-more

Hope that helps