So I've done some more research and while the Kivic unit sounds to be a great solution, it is still not available. So I'm going with plan B. I'm going with an Apple AirportExpress which streams audio from the iPhone digitally and has a built-in DAC and then an analog audio output. Now the DAC is not supposed to be of very high quality, but it seems, from what I have read, that it is good enough to not cause any degradation of MP3s which is what I will be using as the source. If I was using FLAC or other lossless files, I probably could not stand the thought of them being "degraded" in the signal chain, but since I have gotten used to listening to MP3s with bitrates of 192kbps or more, I'm not going to sweat it. If I was really anal about it though, I could add an external DAC after the AE, but again with MP3 source material and beaucoup road noise is it really going to make an audible difference...
Mobridge DA2 > JBL MS-8 > ARC XDi 600/4 > JBL Gti 408 Mids & Vifa OT19 Tweeters; PG Ti2 1600.5 > Morel HCW-10 & IDMax 15