All 12v+ created equal? [metra + LOC]

I'm splicing a LOC into my stock system and it requires a constant 12v+ in addition to the LR+-

I tapped into my metra yellow 12v constant (B) because they're all yellow, but this leaves the "amp turn on 12v+" wire (A) on my metra harness unused like so:


SO, if my theory holds I should be better off, or at least just as well, routing the two ??? wires into the yellow LOC 12v+
That way the LOC is only receiving power when the stereo is on and I have no unaccounted for wires. [amp turn on is labled 12v+ hence the title]

I've done days of research and search, but I can't shake the feeling that I have something about this wrong...

the LOC then has a line going to amp for gain/remote control but I think it doesn't care if the unit itself is getting 12v+ from constant (B), switched (C), or 'amp turn on' (A)
[splicing the front and rear extra wire (A) right into the yellow of the LOC itself seems safe enough]

**The result LOOKS way better if nothing else....***


#moremusing
Theoretically if I understand right you could connect the metras straight through with no addition and everything should work normal; makes me wonder if I should have a local chassis ground on the LOC either way.

In that case running the two mystery cables together into the LOC 12v+ is either the only sensible thing to do, or shorting my system across the front and rear speaker harnesses. . .

If I were to want to install the metra alone just for kicks, no converter, speakers, etc. would I be safe connecting the two ??? wires together?
Where else would they go? They have no companion in the female counterpart.