The unit that you selected will not work with an active PFC power supply. You are right that the Back-UPS does not out put a sine wave. You need to get yourself a minimum of an APC Smart-UPS 750VA LCD. This is the smallest unit made by APC that out puts a sine wave. This unit is a data center unit, sine wave output, avr boost/drop and excellent surge protection. Give it a try, you'll see how well it works.