Needless to say that auditioning so many headphones in such a "short time" isn't ideal. I guess it also was at some shop and not at your home. Did you at least listen to your Source, brought some DAP with your songs you know for auditioning?
I did the same too when I was in germany once, went to a shop that had many headphones to audition I cant listen to where I live, brought a DAP with me and just listened to a lot of stuff, AKGs, Senns, Beyers and high end stuff including Stax 009, Beyerdynamic T1,
I didnt liked most stuff but on the other side, I know this is only first impression after listening to Shure 846 all day/all travel long.
On the other side, I know that once I preferred the He400 over the NAD HP50 (ordered both online in the same time so got them together), and today after first impressions are over its the other way around.
I had a short listen some time ago to the XC and after reading your post, I have a hard time to imagine why youd like them if your preference is the he400.
HE400 is very particular sounding in my opinion and I havent yet heard something similar. I think that my next headphone wont be something that is like a headphone I already own but better, instead it will be something different that will complete the collection of different sounding HPs