@Jumper.. the O2 effectively has 4 gain settings I believe; and they are jumper selectable. Sort of 2x or 6x, or 1x and 3x (some variation on the theme). 1x is very probably your safest bet. Check it out.. at least you can test it and the unit will give you plenty leeway unlike a Magni. You can even order one in that config. Hopefully somebody can weigh in here who's used it.
Thanks for the reply. If you don't mind my asking, how did you arrive at the 1x suggestion - just curious. Also, I'm not aware of dip switches for the O2 - just the external in/out button selecting hi/low gain. I know you can pick the two gain levels for that switch when ordering the O2.