I have recently received 2 units StrongU STU-U6   asic miners which have a PSU which runs on 240 v.  I am in the United States and have 120v wired. I have tested the unit on a step-up transformer (5000w rated) from 120 to 240v which it does work that way.   But I would like to know if it is ok to wire the PSUs by split-phase 240v  --  using 2 110v AC into the lead and neutral input of the PSU.     
instead of using a step-up transformer. 

As a general rule is it an acceptable practice to use split phase 2- hot wires of 120 v each into the input of any 240v input power supply?

Thanks,