I have to say I find it fascinating that you own a device that can do IMO the best headphone surround (Super XFi) by far directly in hardware, and SBX if you for some reason prefer the slightly different approach to headphone surround, and yet you prefer to use the useless Atmos for headphones and HeSuVi for games. Not that there's anything wrong with HeSuVi per se, but I see it as a workaround with its own quirks and issues for when you want to use a device that can't give you a built-in headphone...
768kHz? 😬 You know that even 48kHz covers audio frequencies up to 24kHz, right? So some 4kHz above the threshold of even a perfect human hearing, and even more above the hearing limits of your average adult... I kinda understand some people insist on something like 96kHz, even if only their cats and bats flying by can hear the difference, 768kHz sounds like insanity, to be honest.
Dolby Atmos works differently than other virtual surround solutions. It needs support on the application side to work correctly, and it needs content that's made for Atmos (be it movie or game). Only then can it deliver the full experience. Which also can't really be simulated/approximated by HeSuVi, because it is way more complex than a simple 5.1/7.1 virtualizer. On any other content or without app support, it doesn't really do anything, hence you impression it "doesn't work fully". (It does, it...
I'll see if I can check that somehow, but I've since switched to the SB X3 and I'm using the Super X-Fi, and it doesn't play very well with HeSuVi. So I'd first have to figure a way to make it work again on my system.
I don't remember that happening, but if you're used to hardpanned/unprocessed stereo, then it will certainly sound very different. And generally, it probably doesn't make much sense to use surround processing to listen to stereo music.
Not to knock down the guide, but it honestly feels quite overcomplicated for 10 ms worth of latency difference, which is roughly equivalent to a delay you get listening to a speaker less than three meters away. I used to obsess about latency a lot before I started converting it to "real life" scenarios... Also, ASIO4ALL gives wildly inconsistent results depending on a device. Sometimes it can give you a pretty huge latency.
HPET should be disabled by default on standard Windows installations. And it's also not as simple as disabling it being a guaranteed improvement, it's a lot more complicated than that, depends on quite a few specific things in your system and what works for one system might not work for another one. Generally there should be little reason to even touch it. Same with dynamic tick. And speaking of which, using LatencyMon is also a bit more complicated than simply "you see latency warning in LatencyMon...
No improvement with either the Audio Repeater or Voicemeeter as I suggested? How do you have them set up?