Thanks for the recommendation. Between the he400i and the hd6xx, which one do you think makes the most of the schiit stack?

Hello good people, I am new to this world and I want to make an informed purchase for my next headphones (I currently have a Sennheiser Momentum). After many sleepless nights looking in forums I still can't decide whether to play it safe with the HD6XX or look for other cans. I'm looking for...