IMO - THe E12 has more than enough power and sounds really good with the MD's. At this price point, I believe it is one of the better options available. The plus is the bass response. If I was to be extra critical I'd say the sound leans just slightly dark but that's a preference to me so all the better.
In comparison my ALO RxMKIII sounds much more even and has a better overall sound (but at $600 it should).
I would definitely recommend the E12 as a portable < $150 amp for the MD's. I believe most people would be happy with that choice.
Oh really? Slightly dark? That's interesting... I've read most people say the E12 is slightly bright. But I guess everyone has a different set of ears, haha.
Do you have any opinion on the iBasso d42? The d12 looks great but it's a little more than I was looking to spend. The d42 looks like it would be a nice fit if it would pair nicely - it's small, looks nice, can act as a standalone, and is $188. Is there some downside that I'm missing?