the only sennheiser that i have ever personally liked for gaming is the hd800 but after having them for years they still don’t hold up to other headphones i’ve moved on to. 660s aren’t horrible but the soundstage still isn’t all that big and the depth accuracy on every single set of sennheisers is off. 800s seem big but its a trick and same goes for every other sennheiser, even though the rest don’t have even half of the soundstage of the hd800s. 10-15 feet in game feels normal but then the next 15 feet gets dragged out really hard to what seems like forever and its a guessing game on how far away someone is after a certain point, depending on the game. a lot of them are way too warm and muddy for them to be truly accurate for gaming if you ask me.
on the 990s, the 250ohm is the worst. 600 ohm is best and scales really well as you go up in source gear. they always get called super bright but the 250s are the worst for brightness and even powering them fully doesn’t fix it like it does with the 600ohms. when the 600 ohm beyers are powered right the lows and mids fill in a lot and they aren’t nearly as bright and a cheap pad swap can fix a little of that brightness if you don’t have a strong amp. beyers are usually loved mostly for their imaging first, which is near perfect, but second is their really accurate soundstaging. it may not be the biggest, but it doesn’t have any gimmicks like the hd800s. 10 feet is 10 feet and 40 feet is 40 feet on beyers and direction is always on point.