Using DMM to read amp for common ground.
I have very limited knowledge for using a DMM, enough to be dangerous. I have a pair of SDA-CRS monitors. I would like to check my amp to see if it is a common ground amp. I have read you check between the neg speaker posts on the amp. Where do I set the DMM to get the reading & what am I looking for. I have read it several different ways and I am confused. Should I test with the amp powered on or off. Please help.