[Eschat0n]

Heya!

I currently have a ASUS Xonar Essence STX soundcard (stock OPAMPS) and Beyerdynamic DT 990 Premium (250 Ohm) and I'm pretty satisfied with the sound quality. There's no static noise and I don't mind the treble of the 990.
I've been researching for my next audio upgrade and I'm considering the Beyerdynamic DT 1990 Pro (250 Ohm) with a JDS Atom AMP, and then connect it through the RCA output on the STX (supposed to have a decent DAC).
But then I came across some contradicting information on various forums regarding the use of an external amp with a STX. So now I have a few questions.

Is it a bad decision to connect an external AMP (JDS Atom) with the STX and use it as a DAC? Seen a few people claim that it could damage my components.

Will the OPAMPS of the STX interfere with the external AMP, if I connect it through the RCA output?

I'm pretty certain that the DT 1990 Pro will be a nice upgrade from the DT 990 Premium, but can I expect a noticeable improvement in sound quality from a JDS Atom AMP or should I just stick with the STX and maybe replace the OPAMPS?

As you can see I'm a big newbie when it comes to audio and any help/clarification would be appreciated.
Thank you for your time.

 

[PurpleAngel]

If i was you.
First. make sure the on-board audio is disabled, in the BIOS (not really a big deal).
Then install the Unified Xonar Drivers.
http://maxedtech.com/asus-xonar-unified-drivers/
Replace all three of the STX's op-amps, I used AD797BR op-amps on my STX (around $50-$60 for 3).
(there maybe better choices for op-amps, but I was fine with the AD797BR)
Connect the 250-Ohm Beyer headphones to the STX's headphone jack.
The STX headphone jack uses two of the op-amps, the line-output (RCA) uses all three.
Connecting a amplifier (headphone amp or other amp) to the line-output will not damage components.
The STX can send it's own Dolby Headphone out the headphone jack, but not the line-output (just stereo 2.0 audio).
Technically the Atom is a better head amp, then the STX's, but I doubt you would really notice much difference, with 250-Ohm Beyer headphones.
Another option is just to replace the STX with an external DAC/amp, but I guess with all the taxes you have in Europe, that might get costly.
http://www.audio-gd.com/Pro/Headphoneamp/NFN1128/NFB1128EN.htm

 

[Eschat0n]

Makes sense. I will most likely skip the Atom and replace the op-amps on my STX. Thanks for the reply.