Static noise when running headphones through USB sound card

[Extrachromosomal]

The weird thing about this problem, is that if I run my headphones through my speakers first, and then run the speakers through the USB sound card, there is no static/crackling whatsoever.

The only real difference between the two ways, besides travel distance, is that my speakers are also receiving power from an external source, which might also affect my headphones when they're plugged into the speakers.

Any idea what the root cause could be? As I would like to avoid my headphones going through the speakers.

Specs:
OS: Windows 7 Ultimate x64
CPU: Intel(R) Core(TM) i5-4430 CPU @ 3.00GHz, 3001 Mhz
Motherboard: ASRock H87 Pro4 1150 ATX
Memory: 8GB
Graphics Card(s): Nvidia GTX 760
Sound Card: Asus ROG Spitfire Pro
Monitor(s) Displays: AOC 24" 144Hz - G-SYNC

 

[Louis At Skowhegan]

Never had a dedicated sound card but as usual, make sure the drivers are up-to-date, check for damage on the headphones/card, and make sure you're plugging it in correctly (it happens!)

 

[Extrachromosomal]

Never had a dedicated sound card but as usual, make sure the drivers are up-to-date, check for damage on the headphones/card, and make sure you're plugging it in correctly (it happens!)

As I said in the OP, the problem disappears when the headphones go through the speaker, which then connects to the sound card. Meaning both the headphones and sound card work correct independently, but problems arise when the two are put together.
I appreciate your input though!

 

[Extrachromosomal]

I fixed this issue by replacing the sound card with a FiiO E10K (usb dac/amp), and once again this site was of no help. But hopefully my own solution will help someone in the future.