Headphone/gun/camera/whatever case with foam inside you cut to the shape of your controller
I've seen people at locals with these. The one I linked is probably too big and too expensive, but thats the idea.
This is what I use. Works great.
Try this: https://www.amazon.com/Headphone-Headphones-Removable-Accessories-Description/dp/B00L77JNHQ Geekria UltraShell Case for Large Sized Over-Ear Headphones
I bought these to house my Aventone Planar Reds and it's outstanding. It's designed to hold larger headphones.
I got this one on Amazon. Not super fancy but durable and fits the Dac/amp, cables, etc. and easily fits in a backpack.
Happy I could help you out, and congrats on your newly purchased X2's! As a parting gift here's the case I use for my AD900X's: https://www.amazon.com/dp/B00L77JNHQ/ref=sr_1_5_twi_col_2?s=audio-video-accessories&ie=UTF8&qid=1531877938&sr=1-5&keywords=geekria+headphone+case