So far I've only played the tutorial on SC, but I can confirm it works as advertised in Win 8 x 64 Pro, at least through the tutorial. I haven't tried adjusting audio settings, but everything else I tested seemed to work just fine.

I can also say that Chaos Theory (Amazon Download version) works with Win 8 x64 Pro.

I haven't had the money to get Double Agent so I can't vouch for that one.