grounding problem lang yan sir... try to rewire your system. may amplifier po ba kayo? if meron, ang solution ng mga car audio experts is to use thicker wires (power and ground). plus dapat yung RCA cables nakahiwalay sa power cable kasi they might pick up noise pag masyado magkalapit. if all else fails, and/or tinatamad ka na magpacheck ng wiring ng system kasi siyempre kabit-baklas-latag ng wires mangyayari at kawawa naman auto... pwede na ground loop isolator. hth pO!