How can one determine the phasing between power amps made by different manufacturers? Is there a standard? For example, I own a QSC PLX 3002 and I bi-amp. Much as I would like to own another QSC for my Highs, I can't find one at a decent price. So... I'm looking into a Carvin DCM-600 for the highs and using the PLX entirely for my subwoofers. I want my Highs and Lows correctly phased, but I don't know how to accurately check phasing between amps. Amps are more difficult that putting a DC source on the cabs and watching the cones move.