* Separate grounds for each amp (don't cross the streams)
Can you extrapolate?
* Run each cable from the D-block keeping them as short as possible +/- 6 inches
* Each ground wire must be the same gauge as the (+) wiring. Don't ask why just Google Ohm's Law.
Ohms law makes me sick after EE.
* Use a separate power line to power the aftermarket stereo. I use a totally separate (10 or 12G) positive wire from the battery straight my head unit. I have a separate ground as well ran back to the battery.
Maybe I will (and probably should) do this when I have everything torn apart.
*** I do not have any loop-back issues. The only time I have experienced loop-back is when I plugged my phone charger into the phone and the aux-in 2.5m cable into my phone at the same time. Without the charger no loop-back. With only the aux-in plugged up then no loop-back. If you want to avoid loop-back then follow my install setup and don't use the Toyota factory power & ground (just my belief, not proven).
Loopback is noise? Didn't find much on a Google search. Will continue looking.
Hopefully after a few more posts, the install will be what I am doing not bull****ting on here.
I bought a "4" gauge amp wiring kit from Amazon. Overall people said it is good, and it is a lot beefier than an 8 gauge I saw. (The inners not the outers).
However, just to clarify a few things.
So what I have decided to do, for my own cleanliness, and due to the fact that selling that **** Pioneer amp is impossible, is install the Pioneer under the driver seat and then the Alpine in the jack area. (Some sawing will be required, however only a little due to Alpine amp footprint.) I would put the Pioneer there, however it won't fit easily.
I bought a distribution block from sonicelectronix last week. I will run the + from the battery to under the seat. After looking at your post I could run it the same way you did (rear seat).
I will run 10 gauge wire from the drivers seat to the subwoofer box in the back. (Reminds me, I need to build that.)
Then from the D-block (good term, better than a C-block), I will run to the Alpine amp in the jack area.
Both will have their own grounds, pretty easily. Front I am imagining the seat mount back it will be easy as it is all sheetmetal in the jack area.
From here I have a couple points that clarification would be nice.
First, see the diagram below. It says that I need Y cables to properly connect the Alpine. Is that true? See below. (I am going to run bridged bc I am not running rears.)
That leads into my second question. My HU has subwoofer pre-amp outs (correct terminology?). So should I do the Y cables to the Alpine amplifier, and then run another set of RCA cables to the Pioneer amp from the subwoofer pre-amp outs? Or should I do the Y cables and then run from the Alpine to the Pioneer?
The latter option would be a little cumbersome, because I would then have to run the RCA cable from the Alpine amp to the Pioneer alongside the power cables. Would this matter as far as noise goes, for a subwoofer?
I am guessing all those subwoofer pre-amp outputs do is us a LP filter? See diagram from below for my HU.
Also, as a side note, the Pioneer amp I got says it was manufactured in Dec 2008 at the bottom. Does this still qualify as new? Seem fishy?