So I played music at 69.5 volume with the speakers set at 6+ohms for about 20 min and the receiver clicked 4 times in that period. I set speakers to 4ohms listened at same volume for 25 min and no clicks so far. No difference in sound quality either between the two.

I think the clicking is changing the ohms setting while playing to power the m5s maybe. When I changed the ohms setting the receiver clicked the same way.

I did order a replacement unit to see if another unit acts in the same manner.