I'm installing a new head unit in the trunk. I will not be using the head unit in the dash. This means I need to get power back to that head unit in the trunk. Can I take the speaker wire that is connected to the dash head unit and splice that into the the power to the dash head unit? Then I can disconnect the speaker wire from the speakers in the trunk and power my new trunk-mounted head unit with the old speaker wire This way I do not have to pull up the carpet and run new wire. Is this safe or does it sound like a fire hazard?