Sorry that I'm so late to respond, but I've done some research now and it seems that the ST's output is actually only 10-Ohm like PurpleAngel said(The article: https://www.stereophile.com/content/asus-xonar-essence-ststx-soundcards-measurements). So it seems I am not even getting the 40 Ohm's my...

Come on seriously nobody has any suggestions??

Hey, I've been a lurker on these forum for quite a time but the time has come that I need some help from you dear audiophiles. 6+ years ago I bought this combo(PRO 900 + Xonar ST) through suggestions I found on this site and to this day I love listening to EDM on them. Nowdays I have some money...