Honestly, the dt 990 is one of my favorites but be warned that it’s sound signature is extremely sharp V signature. It can be ear piercing to those who are more treble sensitive. Personally, I think both headphones are great but for more along the point of a persons preferences. DT 880 more neutral sounding less bass yet bright very detailed nice open soundstage and accurate imaging great seperation in comparison dt 990 incredibly sharp V signature mids are recessed very bassy yet very sharp and ethereal like treble again very detailed with a larger soundstage just as good imaging and seperation. DT 880 is the semi open back while dt 990 is the fully open back. Both have a 600 ohm variation that makes them sound much better than their alternative low ohm counterparts and in dt 990s case the treble becomes less peaky and much more refined, as is a seen issue with this headphone quite a lot of people have issues with it’s treble.
I personally like more thump in my bass and am okay with a very sharp treble so I chose the dt 990, I wasn’t a fan of the dt 880. Choice is yours however, if you choose the dt 990 please make sure you pair it to an amp and dac that can help dial back the treble or keep it from going sibilant. Amps like the thx 789 and others have a habit of actually increasing it’s treble causing it to go full blown sibilant. While I don’t think you’ll have issues with the heresy still it’s more analytical I found the liquid spark pairs beautiful with the dt 990 either should work but I personally think the spark does better by the sharp treble of that headphone in particular.
There are ways to tame the treble of the 990 though. Through amps and dacs in particular, however you can also modifiy it by putting extra foam or toilet paper cut to size behind the foam of it’s driver though this will reduce the bass it will also dial in the treble, you can buy a cable filter for the headphone which should fix any form of sibilance. I do recommend if your going to get into beyers consider the purchase of Dekoni Elite Velour. From my experience these are known to deal with the higher treble beyerdynamic headphones by a very great deal and are real comfortable as well. Lastly, the dt 990 does respond okay with equalization though I recommend this as a last resort if your dialing back treble as it can sound a bit off doing this method from my experience. If you are on pc you can utilize the program called PEACE APO it’s two downloads completely free takes a small amount of setup and a potential restart to the pc and your set. This will allow you to tune your sound as well as the quality of the microphone as well if you so choose. If you are looking for 7.1 surround sound like some gamers like look into Hesuvi and Dolby Atmos
If you are unsure on the treble perhaps look more into the new Tygr 300r. I recently reviewed it I will post a link on my own review that you are free to read and decide if perhaps that is more to your liking. It’s more casual more bassy and warm. 🔶 Beyerdynamic TYGR 300 R - #303 by Falenkor a good alternative to this particular signature however is like I mentioned previously one of the philips headphones which you will see me mention in that review. For gaming the philips fidelio x2hr is an amazing headphone as it pairs to the V-moda Boom Pro making it incredibly ideal for the budgeting gamer though incredibly bassy while the shp9500 is the alternative with less bass and more brightness.
This is an edit but I see this is as a subjective question. Though if you want a flat response as some people seem to want. I like the dt 990s more for music and gaming both, yes that includes competitives, but in some genres the brightness can be a bit tiring.