The main difference is in the upper mids and low treble, rather than the high treble, between around 2.5-5.5kHz:

https://crinacle.com/graphs/headphones/graphtool/?share=IEF_Neutral_Target,LCD-X_(2021),Arya_Stealth

The Aryas are a LOT brighter, but in this case a lot brighter is also a lot more correct and normal sounding, for me.

By target curve adherence, I'd say the Aryas are a little over target in that area, but the LCD-X is way under target. EQ largely fixes this. I'd still take the Arya Stealth over it if I could only have one though. Better soundstage, detail, and sounds more natural. Bass slams harder on the LCD-X though.

They are very different headphones, the Arya is closer to the Focal Clear and HD800S (or for that matter the HD650) than it is to the LCD-X. The LCD-X is the outlier that is totally different from the others, all of which have more correct pinna gain.