All (I think) speakers include a "tweeter padding" resistor in series with the tweeter. (This is necessary because tweeter sensitivity generally runs higher than woofers). The MG1.6 has no built in tweeter padding resistor, but you can insert one where the jumpers go. Magneplanar instructions suggest that you do this because the flat HF response of the MG1.6 may sound like too much treble when you play recordings that have been equalized for speakers with HF roll off. The exact value of the resistor to suit your system and your ears remains to be determined, but start with one ohm, which is what Magnepan furnishes with the speakers.
My Maggies are raised about 8 inches off the floor, with open space underneath and I think it helps.