I have been pleased using Odyssey Audio Khartago SE Extreme monos at around $2k and Wyred4Sound SX-1000 monos for a little more $
I have the 1.7s, which are harder to drive than the MG12.
I used to own the MMGs and I had no trouble in a medium room using a Primaluna Prologue One with KT120, putting out around 42W. Real watts that is, and lots of current too.
Your best bet: a single Odyssey Khartago for about $1k