While all of these combos sound pretty impressive, the kludge of cabling with the small USB hub needs some work. Time to build myself a custom cable to clean things up. Or I'll continue to use my Apple certified Cypher Labs Algorythm Solo -dB DAC in a bundle with my iPhone and RSA Intruder. Overall a heavier setup to carry around but it powers my HD800 headphones and is cleaner than the cable kludge of this workaround.
I totally agree. The cabling with any CCK or Lightning-to-USB is not portable-friendly. The best I've been able to do is a 30-pin iPhone 4 (or presumably 4s) with CCK (which is a plastic brick with no cable) to a short USB A to mini USB and then to the microStreamer which has headphone out. Despite what has been said by HRT directly, the microStreamer does put out clean audio at CD-quality rates, and the solution is definitely portable -- in fact, in terms of overall 3D volume, I don't know of a solution that is smaller. The 30-pin CCK lengthens the iPhone some, though, and there is that silly USB cable. If I find a short flexible 4-inch USB cable, though, velcro the microStreamer to the back of the iPhone, and put it in a longish case, it would definitely work for me as a pocketable solution, especially given its thinness.