This one has me a bit stumped. hoping you guys can think about this.

For the most part, i believe i'm grounded very very well. my HU is grounded to my battery directly. My 2 amps are grounded to 1 chasis connection in the right side of the trunk and i also have a cap that is connected to the left side rear of the trunk.

Power wires run from battery to trunk via driver side. RCA's and speaker wire run via passenger side.

My issue with alternator whine is this....the noise only appears when i'm playing a dvd or my mp3 player. When i'm using a regular CD or the radio, it's 100% crystal clear sound. i would agree a grounding issue if it happened across the board, but it's ONLY occurring when on dvd or mp3 player use. i will say my HU (Eclipse 8022DVD) is an 8v preout unit and uses digital cd connection with analog dvd connection.

Would this be an alternator whine or more of a ground loop. I've read a couple websites that discussed noise induced with mp3 players and most used a ground loop isolator to stop the noise, but i'm so sure that has nothing to do with alternator whine..

Ok, what do you think.

 

You could try grounding the head unit at the amps instead of at the battery, so all your audio is grounded at the same spot. Or the big 3 could help as well. (upgrading factory wiring...-batt to ground, -engine to ground, +alternator to +batt). Definitely do these before you do a ground loop isolator, those reduce your output, and you dont want to decrease those 8v preouts.

 

update:

seems like i found the problem. all my grounding was 100% okay. may be a bit confusing but i have 2 inputs and 2 outputs. i use my ipod on 1 input, and my gamecube on the other input. my outputs are 2 headrest monitors. because i want to be able to play music and play with the gamecube, i got a 1in/2out video splitter and the video from the GC went into both input1 and input2. by removing the splitter, all noise disappeared.

now i need to figure out whether i should leave it like this and have the GC work with ipod OR itself or figure out how to split the video w/out bringing back the noise. anyone know why splitting the video caused noise to appear even though i wasn't introducing any additional ground to the system?

 

The spliter itself needs to be a higher quality one than what you had or the one you had was defective. I would just get another, better spliter and go from there.