I've recently picked up a pair of used MG IIB's. They had sat for quite awhile unused. I fired them up as soon as they were delivered. The sound was good but not great. After a day or 2 and several hours of playing, things really improved. I don't know if it was the ribbons adjusting to the ambient temperature or that they needed some burn in from sitting idle. (they actually sound very good for 15-20 year old speakers) I keep the temp round 72 during the day and set back to 68 at night. I don't notice a difference in the performace.
