Geez, I have repeated such observations endlessly, I know it's a long and rambling thread, but..
I don't use the Jot as a DAC, I use a Modi Multibit, or sometimes my Mojo. The Mojo sounds nice through it, by the way- it's a very revealing and powerful amp. The Mojo is a tiny bit relaxed/rolled off in the highs, though- so if that's an issue, it's worth bearing in mind (it's a very subtle effect, I assume it's just a bit of tuning to make it easy and non-fatiguing).
Mojo sounds.. great with easy to drive headphones like IEMs, HD25, Oppo PM-3. It sounds "meh" with middling easy to drive stuff like HE400i. With harder to drive headphones , for example HD650, it sounds frankly awful. It will go loud, but be very boring, rolled-off and lacking in detail.. You can't expect a battery-powered pocket-sized DAC/SE amp to be good at that stuff, really, though.
Jotenheim can drive pretty much anything, it's very clean, quiet and powerful. It's a beast. The only thing I haven't enjoyed on it so far were my SE535s, which sounded a bit thin. Because it's very clear and unsparing, headphones that suffer nasty treble spikes will be a little painful through the Jot. HD700 and HD800 need not apply, though I didn't mind HD800S (might be a bit too much treble for some people).
Essentially, it's an apples to oranges comparison. The Mojo has a lot of compromises in form factor, thermals, and ability to drive headphones, to be mobile. The Jotenheim is a fully balanced desktop amp into which you can add a balanced USB DAC. You'll find that the DAC is fine and competent, but probably not quite as smooth and lovely as either the Mojo or a Schiit multibit.
If you want more of me banging on about the Jot, I wrote a review:
http://www.head-fi.org/products/schiit-audio-jotunheim/reviews/16839
Essentially, I use the Mojo as a mobile sound source with IEMs or HD-25, and my Jot/Mimby as desktop audio source with HD650/HE400i, most of the time. Those two configurations are both very pleasant and enjoyable.