Speakers buzzing but I have no Optical port to stop it. Any solutions?

[decertoyoutube]

I have KRK Rokit speakers and on my old PC I was previously using a DAC to stop the static / buzzing. However my new PC doesn't have an optical port so I can no longer do this, are there any other solutions I could try?

 

[Alabalcho]

You can get an USB-connected sound card with optical out. For desktop PC, you can also get PCI (or PCI-express) sound card with optical out.