Audio-Technica - ATH-AD2000X

Planars are great. But if gaming is your main criteria, stick with dynamic drivers. Beyerdynamic 9 series (900 pro X, 990 pro, 1990 pro) Sennheiser 600 series ( hd600, 650, 660, 660s, 660s2, and including the 490pro) and 500 series ( hd560s is one of the most recommended options for gaming around here), Some of the audio technica ath-ad models. Specifically for competitive fps games, these are pretty much the best options out there at reasonable prices. Adding an amp like the Fiio k5 you mentioned is also a good idea with most of these. I personally like Sennheiser more because I listen to more music than I play video games, but I occasionally get called a cheater in r6 with my old hd600 + Fiio k11. If you don’t care about music or other media, the beyers should technically be even better.

Another vote for the LCDs. Edit: out of OP’s budget, I know. But still excellent headphones for electronic music. So are the Audio Technic ATH-AD2000, which can definitely be found in OP’s budget. Honestly, my 2000’s are still in my top 5 list. 12 years old, but still sound fantastic for electronic music.

My last trip, I've bought: Denon AH-D7200 Sennheiser HD660s Shure SRH1540 Tago Studio T3-01 Audio Technica ATH-AD2000X (New) Previously I've picked up Sony MV1 and Audio Technica ATH-R70x. All of them are used except the AD2000x. And even though almost all of them has a long list of "issues" (mostly cosmetic or "smell") and carry a B grade price (i think they grade them in S, A, B and C), they were all probably better condition than the headphones i have at home. So out of two trips, I basically double the number of my collection. Good job my partner is also a music lover so she claimed a few of them for herself to use.

I’ve been on a journey, I do enjoy my studio monitors quite a bit, I also truly enjoy car audio due to is pure immersive experience, but headphones or IEMs through the right gear is magical. The LCD-GX EQd on the Qudelix gave me this experience. The Alpha and Omega Ra on the new Muse M6 Double gave me this experience last night. I think it’s harder to find that experience with iem as they do not engage the whole body like speakers and car audio do. Openback headphones in general offer such an amazing experience overall. I still daily my ATH AD2000x that have to be at least 10 years old by now. Glad you got to experience it!