Post History

 > _How does this work - how does it improve THD performance?_

As with any transformer connected to a live wire, there will be an AC voltage common mode signal transferred by winding capacitance to the secondary. If you want that common-mode signal to be balanced (and hence easily cancelled by the ADCs differential input), you would use a split burden resistor. 

If your application isn't that important then you would use a single burden resistor and imbalanced ADC input.