Eml synthesizers

I first saw one of these on the bay about a month ago (still there, crazy expensive) but have an opportunity to buy one locally for much less. 

I want to buy it to augment my 100 and most of the controls and jacks seems self-explanatory except for the power ones. There's an in and an out for power and the one listed and the one locally don't come with a power supply as far as the owners know. 

Does the 100/101/200 power it just by connecting it? Why is there an in and an out? Can this be used with a 100 or not? Are there only certain synths that it's useful with?