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
The first thing we should get out of the way is that even though I loved the natural sound of the Arctis 3, 5 and 7, the Arctis Pro sounds better in every possible way. Their sound performance definitely shares the same DNA in that SteelSeries again focused on creating an exceptionally balanced sound signature without a single part of the frequency spectrum that aggressively sticks out. However, the Arctis Pro manages to be even more detailed, deeper and tighter in the low-end and crispier in the highs. You could argue that this is primarily down to the ESS Sabre 9018Q2C DAC integrated into the GameDAC sound card, but I tried the Arctis Pro with several other DACs I have, such as the FiiO E10K, Astell&Kern AK70 Mk II, and Audiolab M-DAC, and it sounded just as good (or better, in case of the truly fantastic $700 Audiolab M-DAC).
A well-balanced sound always results in good spatial positioning. This aspect of the Arctis Pro isn't just good, but exceptional. In PUBG, I was able to figure out where I was getting shot from or where someone's trying to flank me from in a fraction of a second. I heard distant, faint car sounds none of my teammates were able to hear on their headsets. In Battlefield 1, I was completely immersed in the chaos and brutality of the WW1 warfare, again with complete awareness of my surroundings. The explosions sounded massive, but never so overpowering that I was unable to understand the desperate shouts and screams of soldiers around me. In quieter, dialogue-heavy games, or those that rely on ambient sounds and music to build atmosphere, the Arctis Pro was equally impressive.
To put it simply, SteelSeries nailed it. The Arctis Pro is honestly one of the best-sounding gaming headsets I have ever had the pleasure of trying out. When I'm not working on a headset, I use a pair of $500 hi-fi headphones for gaming (the Sennheiser HD 660 S, review pending). If someone took those away and left me with the Arctis Pro for the rest of my gaming career, I wouldn't cry about it at all. That's quite possibly the biggest compliment I can give it.
Since this is a closed-back gaming headset, you shouldn't worry about the sound leaking out. The Arctis Pro does a good job of passively blocking out ambient sounds, as well as keeping the sound of whatever you're currently listening to in and for your ears only.
Music
The same natural and neutral sound signature in games carries over to music. I found the Arctis Pro exceptionally versatile in terms of music genres, equally enjoyable for rock, metal, rap, EDM, and pretty much anything else I threw at it. It successfully keeps up with fast drumming, mighty and multi-layered guitar riffs, and both male and female vocals of various ranges. The music sounds rich, clean and detailed without the slightest hint of veiling or being fatiguing over prolonged listening sessions.
The only thing I found somewhat lacking when listening to certain types of music is the maximum volume. At times, I wanted to crank the Arctis Pro up more than the built-in amplifier allowed me to, especially when listening to songs and genres that aren't as afflicted by the omnipresent loudness wars (you can read more about it
here if you're unfamiliar with the concept). Actually, I was almost always running it at the top quarter of its complete volume range as anything below that sounded too quiet for my taste.
At first, I thought that the built-in speaker drivers couldn't handle higher volumes without noticeable distortion, but they definitely can. My Audiolab M-DAC was able to push the Arctis Pro to significantly louder volume levels than the GameDAC, and the Arctis Pro showed no signs of buckling under the pressure, all the way up to hearing-damage-imminent volume levels.
This shouldn't be an issue if you mostly listen to modern music, which is generally made quite loud in the mix, but if you're into older or classic music, the GameDAC might leave you wanting volume-wise.
The sound performance only gets better after switching to Hi-Res mode, where you can feed the GameDAC 24-bit/96 kHz FLAC files and get the most out of your streaming services with hi-fi playback support, such as Tidal and Deezer.
DTS Headphone:X 2.0 Surround Sound
The Arctis Pro + GameDAC offers DTS Headphone:X 2.0 surround sound support, which is a noticeable step up from the first generation of the technology. The quality of the surround sound will be massively dependent on the quality of the sound design for the game you're playing. Some good examples of games where it adds to immersion and atmosphere are Star Wars: Battlefront 2, Nier: Automata, Destiny 2, and Assassin's Creed Origins. This time around, the simulated surround sound effect isn't bogged down by massive amounts of reverb and a complete lack of bass and precision. On the contrary, the sound presentation stays fairly cohesive. It won't help you become a better gamer in most first-person shooters—stick to the good old stereo in those—but it can add a certain level of excitement in other genres. You should definitely try it out to see whether you like it. SteelSeries made it easy to activate without having to go into the settings of the GameDAC—you simply have to press the flat button on the left side of the volume knob. DTS Headphone:X 2.0 doesn't work in Hi-Res mode, so that's something to keep in mind.