Understandable, but so far things seem to indicate the C5 is better audio quality while the e12 is more powerful. A review over at headphonia says this:
"Perhaps a good base of a comparison is with the popular JDSLabs C241 amp where the C421 outclasses the E12 in overall refinement and soundstage image, but the E12 definitely has the upper hand in power output. I’m still waiting for JDSLabs’ C5 to arrive and compare it to the E12."
And on the jds blog he says in a comment on the c5 page that it should sound as transparent as the o2! :-o