As Matt knows, I'm very much into portable audio also. I have the Mojo. It's very nice for the price, but I don't like the chunky case. I"m awaiting the new Macntosh DS50 I believe it's called. I'm hoping I like it more as it also has crossfeed if you want to try it. I have the ZMF ORi's, Nobel Savants and will be getting the ref CIEM's from Empire Ears soon. The headphone balanced out on my Ayre QX5 is simply amazing and hte best headphone amp I've ever heard and I've heard the top ones on the market many times at stores and shows.
As for phones, I personally don't like the built in DAC's. One of the LG phones has a good built in, but it's still not better than even my bounce around Audioquest Dragonfly Red. The newer iPhone DAC's to me are terrible. If you have good IEM's or cans and a decent portable DAC, just listen and it should pop out at you.
Would I use a Mojo as my main DAC in my home system? Yes I would....if I was just starting out and needed a DAC until I could afford or find a better DAC. As good as DAC's are now days, I greatly miss my analog system that I recently had to sell. I think it just comes down to timing issues that digital has. I've spoken to some designers or gear other than DAC's and they all feel that it's still the timing of digital being off a bit. To my ears analog is just so relaxed when you play the same cut with digital. It will be interesting to hear how the Boulder will sound as their gear is usually pretty awesome and with a server built into it, I'm assuming that takes care of what connection, what cable and what clock to use. They know how to isolate their products and how to use the best power supplies for each part of their gear, so they can solve so many of the problems that are inherent in digital audio replication.
I'm assuming that it should best everything and for 65k plus any discounts, it should. I also feel strongly that digital has come a long way each year. I know two who own Steves' new piece (I owned and loved his old one) and the differences between the two are night and day from what I've been told. That says a ton as he's only one man designing his gear and not a team.
This thread will continue for many years to come as long as Matt decides he wants to keep up with new and latest, lol. Thanks for keeping it on track as that's not easy to do these days. I'm also thankful that it's not full of manufacturers' or dealers selling their gear. Steve and some others have been incredible in their candor and their love of music/gear and not trying to push their stuff. THANKS...