Oh, then that's easy. Just make a bridge diode rectifier with 4 large diodes (or buy one component that has them all together, though power levels may be lower), get a big...REALLY big, like 1000uF or even 4700uF capacitor, and just choose a transformer that will step down the 120VAC mains to a voltage low enough that the voltage you want will be created by the bridge rectifier+capacitor.
You can only pull 1500W max out of a wall socket though (and efficiency is not 100%, so 40V@10A is out of the question, but 2A is very possible at any of your voltages.