I can speak for the M20's as I have owned them twice. They sounded their best when I heard them with a Levinson integrated. I never owned it, just heard it demoed. They can be a little tough to drive, but are very worth it. The bass is very good for the size and the imaging in incredible when they are set up right. I owned the M20's with a few different amplifiers and the match I prefered the most of what I owned had to be the audio refinement complete integrated. Warrenh used to use the M20's with a YBA. Which is in the same family as the audio refinement.
