I find the Audio Aero to have higher resolution(in particular mids and highs). But what really makes the Audio Aero player better in my opinion are the calm and controlled way that presentes the music. I find the EMC-1 mk. II. slightly stressful compared to the AA. As Bwhite puts it very lively but not life-like.
I have just been to Frankfurt high-end show, and the new mk. II version of the Capitol was in about 4-5 rooms. Even though we are talking show conditions all these rooms represented some of the best sound at the show. The bass of the Capitol has improved and the ease of the sound has also improved a notch. (again show conditions are not very useful for listening, but that was my main impression).
I think I am getting the new version!
I have not heard the Mephisto.
Don't to ask futher questions.