Nope, I would not sweat the turn-on wire. Its not part of the signal path, so no chance of noise being introduced. It draw squat current wise, so it will not draw down what ever battery bank its on. If your boat is utilizing a traditional dual battery switch (OFF/1/BOTH/2) and no ACR/VSR, then the audio equipment should all be pulling off the C post of the switch. In this case, everything is sharing the same battery......which ever one you have the switch turned to.