The Xonar DX just installed and tested with my Beyerdynamic 990. Bin is actually been a person who is difficult to convince to take money for a sound card in your hand but ...
Damn it worthwhile.
In conjunction with the KH Beyerdynamic the sound is really very good.
Absolute recommendation that remains in it.
Update:
Unfortunately, the card will probably not in the system and also my initial enthusiasm now has its limits ...
I quickly realized that I had been given a relatively strong noise. When listening to music, Windows, etc. This error could be shut down by the playback settings to raise the quality under the Windows sound options. Problem solved but ...
In games the error persisted. I have tried everything and found a solution. Whether other PCIe slot, latest drivers, enough distance from the graphics card etc ... no chance.
In other words, in any 3D application noise is bestowed. This begins softly and increases until it is gone again and again gets louder - always alternating.
Asus Support statement from 27.07.13: All of our systems are running properly, we utilize only Asus sound cards.
Apart from the many micro-hum in the TS / Skype have noticed just as the helicopter issue also in games. Just looking to Asus Xonar googling noise, because there a lot of these problems, unfortunately without a solution in 3D mode.
I'll try again the Xonar STX, also shows the error also appear in my system to not work the card.