I'll split the audio performance analysis into two parts - gaming and music. Even though the headset produces the same sound regardless of what it's being used for, you won't necessarily look for the same things while annihilating your virtual opponents as you will when listening to your favorite tunes.
Gaming
As expected, this is a serious gaming headset, one that's designed to give its users a competitive edge over their opponents. At the same time, HyperX didn't make it too sterile. The bass is very present and quite thick, but well controlled, which keeps it from spilling into the midrange enough to cause any problems with the clarity of vocals or the detection of footsteps. HyperX actually found a great balance between precision and pure enjoyment. The Cloud Revolver S manages to offer quite a bit of both, regardless of which game you're playing.
I had no trouble picking out my enemies and the direction they were closing in on me from in PlayerUnknown's Battlegrounds or Battlefield 1. In terms of sound-source separation, this headset's stereo mode works great as long as you stick with the default sound profile. That's the one where no white LEDs on the sound card/control unit are glowing.
There are three other sound profiles you can switch between by pressing the button on the left side of the sound unit - Bass Boost, Flat, and Vocals. The Bass Boost profile makes the bass even bigger, overemphasizing it a bit too much for my taste. To compensate, it also increases the presence of the midrange, so the resulting sound isn't bad at all - in fact, some users might even prefer it over default mode. Not me, though. There's just too much of everything without as much of the subtlety as with the default sound profile. The Flat profile sounds lifeless and boring; I have no idea what they were looking to achieve here. Perhaps it's for those who find the default bass level a bit over the top? Finally, the Vocals profile puts a strong emphasis on the middle and upper frequencies, making them more pronounced, while the bass gets pushed back. I didn't care much about this profile, either, as it destroys the airiness and warmth of the sound that's present when the default profile is used.
The passive noise isolation is excellent; there's no sound leaking through the ear cups at all, and HyperX managed to achieve that without making the clamping force too high - lovely!
Music
The HyperX Cloud Revolver S is a sweet-sounding headset. It's not too focused on absolute accuracy, but the controlled thickness of its bass and satisfying presence of its mids and highs make it very good for listening to music. I would have no problem with making this my daily driver if I were looking to use only a pair of headphones for all of my needs. That's a good thing to know considering this headset's hefty price.
I can't really point out a genre of music it handles exceptionally well or surprisingly poor - it's a nice all-arounder, every bit as good for hip-hop, rock, metal, electronic, or ambient music. I even played some Slovenian polka, just for the fun of it - the tuba sounded thick and full, the trumpets were crisp, and the clarinet carried the melody beautifully. All jokes aside, the Cloud Revolver S is simply a lovely performer regardless of what you use it for. It kicks and punches and is loud and clear, a real pleasure to listen to. You get your money's worth.
I tried to connect the HyperX Cloud Revolver S to a couple of external USB DAC/amps to see how they would change its sound characteristics. I did notice some slight improvements in the overall presentation after pairing it with products like the Cambridge Audio DACMagic XS V2 or Audiolab M-DAC, but I do need to point out that the supplied sound card holds up very well in every regard. It has plenty of amplification, and the built-in DAC seems to be pretty good as well. I ran across a couple of forum posts where owners of this headset complained about the provided sound card having some sort of an audible hiss that could be heard when nothing was playing. No such problems with my sample - no hiss can be heard at all.
7.1 Surround Sound
The HyperX Cloud Revolver S supports Dolby Headphone 7.1 Surround Sound, and that's one of its key advantages over the "regular" Cloud Revolver according to HyperX. Dolby Headphone 7.1 Surround Sound can only be used when the headset is connected to the provided USB sound card, and it's activated by pressing the biggest button on the sound card itself.
When it comes to headset performance with surround sound turned on, my feelings are mixed. When you press the button, the sound seems to immediately get louder as it pushes forward, closer to your ears. It grows in vertical direction as well, so to speak. All of that happens without any significant loss of bass, which is a major drawback of most other gaming headsets in surround mode, but some hollowness is definitely introduced to the sound's presentation, so the vocals can sound a bit echoy and slightly harsh.
All of that does result in a feeling of fullness and width of the sound, but I can't say that it in any way helps with spatial awareness and the ability to accurately position in-game targets. Both of those aspects simply work better in regular stereo mode. For example, that added "height" of the sound can trick you into thinking that your enemies are in a room above you when they are actually behind you. In a game like PlayerUnknown's Battlegrounds, that means you'll end up in the lobby instead of eating your chicken dinner, with the surround sound to blame.
Overall, you should definitely give it a try, and it could possibly even become your mode of choice for offline games and movies, but I don't see anyone remotely competitive using the Dolby Headphone 7.1 Surround Sound feature of the HyperX Cloud Revolver S in an online shooter or any other game where it's important to know where your enemies are coming from.