[Eltron97]

   
Creative Labs Sound Blaster Z sound card.
 
There is also USB DAC/amps, like the FiiO E10K and Schiit Fulla.
 
I think you really only need to spend under $100, for something to drive the HD558 headphones.
 
Here is the aftermarket cable ($14 to $22) I use with my HD558.
Comes with the 3.5mm (1/8) plug and in one of five lengths
.http://www.ebay.com/itm/Replacement-Audio-upgrade-Cable-For-Sennheiser-HD595-HD598-HD558-HD518-Headphone-/261255113290?var=&hash=item3cd404aa4ameOf9Ps7ftSDxE6VdffOkcg

Dumb question: Would buying an external amp/dac make an internal soundcard (like the Soundblaster Z) unnecessary? I´m asking because I wasn´t sure if you were recommending getting the Soundblaster Z in combination with an amp/dac or if you were talking about two different solutions... Sorry to bring this up again

 

[PurpleAngel]

  Dumb question: Would buying an external amp/dac make an internal sound card (like the Sound Blaster Z) unnecessary? I´m asking because I wasn´t sure if you were recommending getting the Sound Blaster Z in combination with an amp/dac or if you were talking about two different solutions... Sorry to bring this up again

 
When you connect a USB DAC or USB DAC/amp to a PC, it bypass internal sound cards, internal or on-board.
So the Sound Blaster Z (& motherboard on-board audio) would be bypassed when you connect a USB audio device.

 

[Eltron97]

Ah, alright, I get it. I was a bit confused there... Having an internal soundcard is probably worthwile because it offers quite a few options (like surround sound) which can also be turned off. However, I´m wondering whether the Soundblaster Z´s audio quality is better than the onboard sound of a good motherboard (e.g. the Gigabyte GA-Z170-HD3P which also offers surround sound)? 

 

[3rdAmigo]

I am in the same boat as you Eltron, just built a new gaming PC.
 
What about an external sound card/Amp/ dalby surround all-in-one? If there is such a thing?

 

[PurpleAngel]

  Ah, alright, I get it. I was a bit confused there... Having an internal sound card is probably worthwhile because it offers quite a few options (like surround sound) which can also be turned off. However, I´m wondering whether the Sound Blaster Z´s audio quality is better than the on-board sound of a good motherboard (e.g. the Gigabyte GA-Z170-HD3P which also offers surround sound)? 

 
The audio quality of the (from 2008) Realtek ALC887 audio processor built into your motherboard might be bested by a $25 Asus Xonar DG sound card.
I would assume that the Realtek ALC887 does not do any worthwhile headphone surround sound.
Guessing(?) the Realtek audio drivers are kept simple, for better stability.
 
For headphones like the HD558, guessing up to around $100 is about as much as you would want to spend to improve their audio quality, with a computer.
I usually push the FiiO E10K, Schiit Fulla, Sound Blaster Z.
 
Or a Asus Xonar DX sound card (used $50) combined a FiiO A3 (E11K) headphone amplifier ($60).
The DX provides a good DAC function (CS4398 DAC chip) and Dolby Headphone surround sound.
But it's headphone jack's high output impedance is not the best for driving headphones, but it seems to work great at sending a good audio signal to an external headphone amplifier.
The A3 amp can be powered off USB or it's built in battery, so it can be used with more then just a computer.
Like plugged into a smart phone's headphone jack or anything that provides a line-output analog audio signal.

 

[Eltron97]

Thanks for your advice, you´ve been a great help! Now the question is whether I will choose the "amp/DAC way" or the "soundcard way"... Am I correct in assuming that, choosing the Soundblaster Z, I could always disable all effects (like the surround sound) in order to get the pure, unchanged stereo sound? I´m asking because it might come in handy if I´m able to switch back and forth (surround/no surround) which I wouldn´t be able to do with an amp/DAC.
 
P.S.: Is the microphone that comes with the Soundblaster Z any good?

 

[Eltron97]

  I am in the same boat as you Eltron, just built a new gaming PC.
 
What about an external sound card/Amp/ dalby surround all-in-one? If there is such a thing?

If your new gaming PC does not include an internal soundcard, your source of audio would be the onboard sound of your motherboard which probably does not have many fancy features. It simply depends on what you want: In case you would only like to enhance your sound quality an amp/DAC like the Fiio E10K or the Schiit Fulla could be a good solution (importanty, these are limited to normal stereo sound). If you need features like a surround sound simulation for your stereo headphones, though, you might want to either build in an internal soundcard (e.g. the Creative Soundblaster Z) or search for a good external soundcard. I hope this is of any help to you.

 

[PurpleAngel]

  Thanks for your advice, you´ve been a great help! Now the question is whether I will choose the "amp/DAC way" or the "sound card way"... Am I correct in assuming that, choosing the Sound Blaster Z, I could always disable all effects (like the surround sound) in order to get the pure, unchanged stereo sound? I´m asking because it might come in handy if I´m able to switch back and forth (surround/no surround) which I wouldn´t be able to do with an amp/DAC.
 
P.S.: Is the microphone that comes with the Sound Blaster Z any good?

 
I believe you can disable the SB-Z's effects, but I'm far from an expert on the Creative Z series cards, as far as changing settings.
 
Best to ask questions about Creative Labs cards om this links.
http://forums.creative.com/forumdisplay.php?f=6
http://www.head-fi.org/t/623079/creative-sound-blaster-new-series-z-zx-zxr
 
I believe the microphone that comes with the SB-Z is decent.
The SB-Z I bought (used) did not come with the mic, so was never able to test it myself.
But try asking about the mic on the links above.
 
Now some people do prefer to use a USB/DAC/amp, instead of a sound card, they just prefer gaming in stereo.
Asking about PC gaming on these links.
http://www.head-fi.org/t/534479/mad-lust-envys-headphone-gaming-guide-5-31-2015-beyer-cop-and-shure-1540-added
http://www.head-fi.org/t/593050/the-nameless-guide-to-pc-gaming-audio-with-binaural-headphone-surround-sound