Haven't been on this thread for a couple of months -- but funnily enough, I missed out on the news of the HRT microStreamer and iOS 7.1. I had stuttering with hi-res files under 7.0.X with the connection
iPhone 5 -> Lightning CCK -> microStreamer DAC
but now with 7.1.1 it works just fine. It seems that Apple is fixing things under the hood with regard to hi-res audio.
Something tells me with the Beats purchase rumors and these subtle changes to iOS 7 behavior that we're going to get native hi-res support in the Music app on iOS. In my mind, that is really the last step that needs to happen. Going to a secondary app to play music when there's the Music app already there is kind of silly.