So I have spent some time listening to the E12. Bottom line: I'm very impressed. I even hooked up my LCD2s to the portable amp, and it manages to drive them to excessive sound levels. The background is completely black - even with the volume knob at 100%. It probably wouldn't be fair to compare it against my Violectric V200 (at 10X the price), or my O2/ODAC combo (much larger, and also a DAC). It is however, definitely the best truly portable amp I now own, and that's compared against the E17 I have, and the E7 and E11 I have owned in the past.
I'm quite thrilled with it, honestly, as I have now reached end-game with all of my headphones. I'm completely and totally satisfied with my LCD2/Violectric V200/ODAC/Mac Mini combo in my living room, my M-100s at work with E17 as Optical SPDIF and E09K as amp, and now my E12 and M-100s with IPad/iPhone, LOD, and 30-pin adapter(s) for travel/on the go portable use. I can only hope FiiO comes out with a Lightning-native LOD cable for iDevices...