I had ML Aerius, and would advise using at least a tubed amp, fussy as they can be. Not sure what your definition of "mid-fi" is... the ML's are not mid-fi. Try a VTL Stereo 80 or similar amp which provides at least 40 watts/channel.
For pre, you can go solid state; I used an audio research LS-3 with great results. Also used a tube preamp, a Counterpoint 3000--very dimensional with the Aerius...
Enjoy. -Ed