high headphone noise floor in Windows 10 bootcamp

Just received the IEMatch, tested and confirmed it fixed the noise issue in Windows (noise is basically imperceptible with the IEMatch connected). It makes a much bigger difference than I was expecting actually, it even reduces the noise floor and removes some resampling artifacts from other sources like macOS and my phone.

Yes, I tested with sound from multiple different apps (chrome/youtube, spotify, steam, notification sounds, even the test chime in control panel). The noise floor is silent until the sound starts, immediately kicks in when the sound starts, and the noise persists for around 30s after the sound stops.

Yeah I realize that, it's not the biggest deal but still slightly annoying for using Windows when not at my desk. I don't have access to an actual Windows PC to test, but I am pretty confident that it won't be nearly as bad.

I'm still pretty surprised by the amount of noise difference between the two OSes on my identical hardware though, so I still think it's an issue with my bootcamp config and not with Windows itself. I'll probably try installing older versions of windows, or testing on my old MBP to see if I can diagnose the issue.

After a lot more testing, I now think that you're probably right that this isn't a bug and that macOS just handles my specific IEMs better than windows. I tested with normal Apple wired earpods and they sounded fine, couldn't hear the noise floor at all. A frequency analyzer comparison also didn't work since the difference in noise was actually lower than the input noise floor of my audio interface lol.

I guess my solution will be to get a hardware impedance adapter like an iFi IEMatch which should solve the issue. Thanks for all your help though!

Nope, I have a USB dac/amp and I can't hear any noise floor when outputting to that. Haven't tested HDMI but I'd imagine it should also be fine.