Oh man...twister6's review on both and your post really made me curious about this E12A.
I already have the C5 (and E12) but I think it's nice to have another excellent amp with a different soundsignature.
In the end it's all about synergy imo. Just curious, what headphones / iems did you use with C5 / E12A? Can't find them under your profile...
Gosh, right now mostly IEMs. The ones I have in my portable bag are the Audeo PFE-232, Sony XBA-H3, Sony XBA-40, HiFi Man RE-600, and Westone 3.
I also have started using the crisper sounding Audio Technica CKN-70. I fire up the KEF M200, Audio Technica IM-50, and TTPod T1E sometimes, too.
Those are the main IEMs I use out and about, though I have other IEMs that are good but don't see much air time.
For portable going-out headphones, I generally use the Thinksound ON-1, Martin Logan Mikros 90, Logitech UE6000, Audio Technica M50x, and Sennheiser Amperior. That's for out-and-about. I don't usually use my open cans or more bulky/high-end cans outside my house.
I actually also have two E12DIY amps running different chips, too, so many different flavors of IEMs, phones, and portable amps.
Of course, not everything sounds good together.
Yes, you are right - there are certain synergies, some really great sounding pairings, that you'll find based on your listening preferences. Other combinations will fall flat on their faces, or just not offer anything special.
I actually set up a Google Doc so I could keep track of the pairings that sound especially good to me. Otherwise, I would forget with all the different permutations!