I got an iFi Micro iDSD used for around $250. Although I can't comment on any sound comparisons, I picked it over the Schiit Stack or o2+odac for several reasons:
-it's portable
-it has a bass boost switch (it's subtle and well-implemented)
-it has 3 impedance modes + 2 more iem impedance matching modes, and it's loaded with other features
-once you look at and hold this thing, you know you're holding a quality product that's built to last
-it used to cost $500, so I felt like I was getting a bargain haha
I think the main thing is that when I upgrade my dac and amp, it'll be nice to still have a very good portable dac/amp I can still lug around.