Sorry, I'm unpackaging as I moved the day before yesterday, so it takes me a while till I can answer. I would say it's going to work no problem with the S3.
Using any usb DAC in your phone makes it to drain quite fast. I don't think I have any records of that but I will have them at some point during this week. I sold the combo a month ago because I needed the money back, but I am ordering a new one today or tomorrow. I still have two O2+ODAC combos to be assembled some time this week.