yap,i agree w/ kral to use star grounding system to keep it intact and less prone from loose connection unlike the daisy chain grounding,because once you have a loose ground connection noise will be generated from your system.and @ the same time i agree w/ bws to use resistor or capacitor for the dc voltage before connecting to the chassis ground from which the ac is connected because,dirty ground is high voltage and clean earth is (low voltage grounding dc) and it's not a good practice to mix the two grounding system together,otherwise noise will be generated again.thanks and more power.....