I have an AT&T iPad mini pre-ordered on Day #1, and when it arrives in 2-3 weeks I'll try it with a number of DACs.
My favorite portable DAC for the iPad 3 so far is the Pico DAC, which just sounds more transparent and spacious than my iBasso D4 for example. It's strange that on my Macbook Pro that these two DACs sound closer to each other than when using the iPad as the digital transport. Always thought maybe it was a jitter issue, and the Pico DAC with up-sampling and re-clocking can reduce jitter more than the non-upsampling DACs.
My Lighning to USB CCK is already here, so I'll be ready to test things right away.