hello. i have a sunfire signatures series 2. 425x5. i can hear a slight crackle in the right channel at certain times. like a hollowness. i switch the banana plugs to left side and the sound moves. i switch the rca sound does not move.leading me to believe amp is problem. about system...onkyo avr.monoprice rca.polk lsi15 speakers.monoprice wires.and monster power strip-currently no power conditioner.(could that cause this?) amp was claimed to been completely serviced to specs. anyone know this problem please help.