Front left channel question for the really smart guys

So, like an idiot, i connected an amp to my factory head unit, despite what everyone told me. I will probably cave in this summer and buy a new head unit, but don't want to install a mic next to my existing factory mic in the overhead console. Has anyone ever tapped into the factory mic on a 2012 non-JBL head unit? That's the only reason I have for not upgrading - the factory set up works great for Bluetooth calls.
Anyway, for those out there, thinking of doing the same thing: Even though I used an Audio Control Epicenter Plus to convert high-level inputs to RCA level, and also combat the "disappearing bass when turned up", I'm still having a problem. The problem is that I was hoping to use the "GTO" signal-sensing for a remote turn-on for my amp. Problem is, when I start my truck, I get snapping/popping from my amp turning on, even if my head unit is turned off. I talked to someone at Audio Control (GREAT folks and products, by the way), and he mentioned that the front left channel is responsible for some things like door chimes, bluetooth, etc. So, even though my stereo may be turned off, the Epicenter Plus still senses a signal on the left front channel whenever the ignition is on.
My question for the experts here - should I connect my Epicenter to the rear channel speaker lines instead of the fronts? Will that screw my ability to use the Bluetooth altogether? Or should I just buy a new head unit and tap into the existing mic in the overhead console?

 

I've been without the factory HU for about 6 months now, but from what I recall there wasn't any chime noise from any speakers and bluetooth played through all speakers. You can definitely connect your epicenter to rear speakers instead, but you will lose all fade controls from the HU (if that's even a concern for you).

Does the epicenter turn on, too, or it just the amp? Can you connect the epicenter turn-on to an acc +12v source instead? In my past car, the auto sense feature of my JL amp was finicky so I connected to an acc +12V source and never had any problems for the +5 yrs after that.

I've heard of people having success integrating the factory mic with pioneer HUs. I have a Pioneer HU, but elected to install the Pioneer mic instead. I didn't want to hack into the factory wiring, because I don't plan to keep this truck forever.

 

I know for a fact that on GM's all of that goes through the front left speaker. I'm pretty positive it does all speakers on Toyota's like the guy above me said. Also to solve the popping sound all you should have to do is add a 1k-1.5k resistor on the remote wire going into the amp. That should be the easiest and quickest fix. Or just find an accessory source at the fuse box and use that to turn the amp on instead.

 

The Epicenter turns on, which then turns on the amp, with a bunch of popping, sometimes squealing sound. Definitely not pretty.
I might try connecting to the rear channels instead of fronts. I don't have any fade control anymore, the way I've connected, but for some reason the staging seems a lot better that it was before amping. Factory set up had really strong rear stage, in my opinion.
Will post results when I try some wiring changes.

Thanks to both who responded.