"For reference, my ears are too big for the ATH-30x."
I know just what you mean. Some gaming headset users may not agree, but here's what I'd recommend. First, avoid gaming headphones altogether. Some say there are some decent gaming headsets. I've tried HyperXCould2, and while maybe better than most, still cant recommend them.
You can get far more value for your money if you get a quality (not necessarily expensive) pair of headphones, and attach your own mic to them. Scroll down a tiny bit here and you'll see an excellent example
http/lifehacker.com/how-to-turn-your-favorite-pair-of-headphones-into-a-hea-1520291511
A vid that gives ideas on DIY low price gaming headsets
https/www.youtube.com/watch?v=3fD-M1F6L4g
For higher end sets
https/www.youtube.com/watch?v=VgTnJ3JQQ0E
For the price, here's some decent over ear, comfortable, quality headphones for bigger ears, within the limit you stated... http
/www.audio-technica.com/cms/headphones/591d1ba45202f375/ or, for a bit more, maybe these http
/www.cnet.com/products/sennheiser-hd-598/
This is an attachable mic, for like $8, $9 if you want an audiosplitter, or extension cable: Zalman Zm-Mic1 High Sensitivity Headphone Microphone. There are other attachable mics for a tad more. Of course, the best bet would be the latest version of the Modmic. http
/www.modmic.com/ They offer some good headphones as well.
Here's what some reddit users have to say on the subject https
/www.reddit.com/r/headphones/comments/3gxi14/gamingpc_headsets_for_people_with_big_ears/