i had totally forgotton what you were trying to amp.
for most parts e12a sounds better, but if you are trying to amp something that is a little more demanding, e12a will not be fit. Considering only what is shown in your profile, e12a, but you should come to e12 thread and read there what is recommended too.
On the other hand, i would seriously buy headphones, considering your actual inventory, e12a would not add that much. For example, on ie8 it adds soundstage, clarity and detail, but not to such degree that ie8 becomes ie800, it adds a little of these.
consider that at 200$ price tag you could fiind a deal on a pair of ie80, or hd598, or ultrasone dj one pro, or urbanite xl, or momentum over the ear, or some other headphone that would float your boat much better than adding an amp to your current headphones. this is not because i know, but because e12a does not chang the sound at all, it adds a little detail, and a little clarity, but not enough to be that much of a worthwhile upgrade if you don't already love tonality and general sound of your headphones... on the other hand, if you already loved your headphones, e12a brings everything to another level.
i still think that you should ask the exact same question to some superlux owners, i have zero experience with them, they might be hard to drive and sound better on e12.
Anyways, i would also advice you to not rush and spend some time testing, and if not possible, choose a place with at least 15-30 days return policy.