I'm sure it will play at .5 ohm but, is it stable at .5.....probably not. It's pretty rare to find an amp that is stable at .5 ohm. Like I said, it will probably play at .5 ohm but, it will heat up a lot faster and the risk of damaging the amp is a lot greater. Damaging that amp would be a shame because I know that anything Arc Audio is pretty pricey. So, if I was you, I would only run it at 1 ohm unless you only plan on playing it for short periods of time. Also, most warranties won't cover damages cause by running the amp at to low of an ohm load.