Where should I run my power wires for the head unit

[Bun-Bun 10+ year member]

Ok going to do this finally. But where should I go with them?

Current setup. Stock battery up front with a AGM in the trunk. 1/0 running from front battery to alternator and starter. 1/0 running from alternator to trunk battery (pos and neg with 300amp relay between on pos). 1/0 from trunk battery to distro to amps (pos and neg). Head unit using stock harness.

Going to run 8ga (pos and neg) to the head unit. But should I go to the front battery, the isolator relay, or the trunk battery?

Front battery or isolator will be the shortest run. I have read that connecting to the front battery can still be problematic for ground loops. Isolator being a shorter run and not directly off the battery be cleaner? Going to the trunk battery would be a longer run of 8ga but would be the cleanest. Plus with the car on accessory the stereo would be completely isolated from the rest of the car (relay is only closed when ignition is on).

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[All_Logix 10+ year member]

I see your problem, I am no stranger to those ground loops that just wont seem to go the **** AWAY! haha, Honestly though, I would probably get your power from either the front or back battery and ground it to the spot where your alternator grounds to the frame or engine block. This is honestly the best possible ground I can think of in a vehicle

 

[Bun-Bun 10+ year member]

I don't use common grounds for anything stereo related. I have separate pos and neg runs for everything.

Trunk battery makes the most sense I think. Because then everything stereo related is getting power and grounded to the same point, the trunk battery. Even if it is slightly longer run. But it is also 8ga for a HU.

 

[Bun-Bun 10+ year member]

Ok well I decided the back battery was the best place. Went ahead and ran the wires.

View attachment 26531889View attachment 26531890

Solved some things (SNR is better when playing CD's). Alternator whine almost non existent. But my noise problems are still here. On with the troubleshooting!