I appreciate all the suggestions so far. If I want to save a little money, a Schiit stack sounds like a great option. I'm also a little curious about the SMSL M6 which someone has reported is roughly equivalent to a modi/magni 2 stack, and costs $169. OR... and this is a big or, I could just get a Chord Mojo and call it a day. I'd also be able to use my Fiio X5 as a transport with it. The only issue with it is I worry I don't have good enough ears to justify spending $600 on a dac/amp... which means finding a place for an audition might make sense.
For now though, I'm using a Fiio X5 as DAC going to a Cayin C5, and I love the combo with my HD700, just absolutely love it. So, I suppose I really do have some time to make a decision, although I really do wish Chord Mojo sold for $600 on Amazon, where I have some credit... it'd make the decision a bit easier.
Oh yeah, also, I'll have to make sure whatever I do end up getting will be fine with a Senn IE800 too.