I owned the original minimax (modded) and agree it is outstanding for the money. Have not heard the 'plus' but assume it's even better.
I now own the Calyx and feel it is superior to the Minimax. Well worth the extra cost. Only caveat, with the Calyx you definitely need to spend a few hundred bucks on a good usb cable, it makes a huge difference.
Differences between the EE and Calyx - the EE is very organic and musical. The Calyx is more neutral and refined, with better detail, air and sound staging.
Still, could be happy with either.