I need to know how to make sure that an amp has a common ground. I vaguely remember something about measuring between negative's with an ohm meter and it has to measure below .05 amps...????? Sorry everyone, I'm looking at an amp that I like and want to make sure it works with my SDSs. I'm hosting a little party at the moment (with my SDSs groovin in the background) and can't be rude by sitting on my pc trolling the Polkie Forum. Any help is much appreciated!!