Reversed polarity can make a noticeable difference, but I notice it more with tubes than solid-state gear and if you have speakers with a crossover in the midrange it then the question of proper polarity could be moot.
That said, I think it's nice that ML provides the option for those that can hear the difference on their particular systems.
That said, I think it's nice that ML provides the option for those that can hear the difference on their particular systems.