@Brandon_Satterfield identified it as 600W, so legit. 
I now see someone posted showing the power supply for that spindle which is 110V 8A, and 600 W / 110V = 5.45A — that should be capable of handing even an 800W spindle since 110V * 8A = 880W. Looks a lot like this kit. I was just barking up the wrong tree looking at the 48V power supply.