I canno't comment based on sound as I have not heard the components you mentioned in the same system together, as a system. Also I have not personally heard the EC other than the reviews I have read.
I can only say, if sound is your ONLY consideration - then you will have no choice but to listen to both amps in the SAME system AND same room. There are far too many variables involved.
Provided you intend to hang on to your amps for a long time - The Mac is your best bet for reliability, resale value & ofcourse sound.
I have owned the MA6900 previously & loved it! It was a very musical amp. Good luck with your search.
I can only say, if sound is your ONLY consideration - then you will have no choice but to listen to both amps in the SAME system AND same room. There are far too many variables involved.
Provided you intend to hang on to your amps for a long time - The Mac is your best bet for reliability, resale value & ofcourse sound.
I have owned the MA6900 previously & loved it! It was a very musical amp. Good luck with your search.