Long story short (and skipping over technical details, although I am happy to provide them should anyone be interested) I basically have a fairly severe problem with hiss and VRM noise being injected into my PC speakers, particularly in games. I have spent numerous hours looking into this with oscilloscopes and what not, and have managed to build dedicated processing circuits to get the speakers silent while idle, but although reduced, the noise is still an issue in gameplay.

ATM it looks like I have 2 options:

1 make a auxiliary supply for my sound card,an Asus strix Soar which uses a 6-pin PCIe connector for power to try further isolate the card from the other system components.

2 try to get the card outputting a balanced stereo signal.

option 1 is fairly easy technically, but will be annoying to actually implement in a usable manner. Since the card supports 7.1 surround, I see no reason why the eg the front and rear channel can be used to output a balanced stereo signal. Since there is less risk of breaking my sound card, I am leaning towards this option. Does anyone know how to do this?

I am also open to other options, however the standard stuff such as trying different power outlets and ground loops makes no difference. I can explain the technical reasons if anyone is interested. However I do not wish to buy extra gear such as USB dacs etc.
Thanks in advance