That's interesting indeed. What about it sounds worse on the MS2/Asgard? I'm thinking maybe Schiit amps' tendencies to be somewhat bright might not mix well with the 1350s. I've got the MS2 and MS2+ and they do seem slightly different. The MS2 has a slight bit of grain and coloration in the mids but its very slight and the MS2 is still pretty great for the price IMO.
For whatever reason, the 1350s just sound a little dull and lifeless on the MS2/Asgard combo. I could speculate all day as to why that is, but who knows if I'd be right. On the Audinst, the 1350s just sound a little more snappy and transparent. It COULD simply be that I need to spend more time with the 1350/MS2/Asgard combo to allow my ears to adjust to the sound, but my initial snap impressions have been pretty meh.
Now, with my DT880s (250 ohm), the MS2/Asgard combo really shines, while the Audinst just doesn't do them justice. This seems to be due to the Asgard supplying them with enough juice to really let the 880s shine.
All in all, it's worked out well for me. The Audinst now permanently resides on my work computer where I do all of my 1350 listening anyway. The Asgard/MS2/DT880 rig is my permanent fixture at home.