2013 Tundra CM Stock Stereo issues!

So.... Here's what's going on and I'm starting to really feel like a dumbass!
Driving down the road talking on the phone and heard a "POP". Then the phone was really quiet. The left front speaker quit working, the left front tweeter used for the phone sounded blown. Since they are wired in parallel, I replaced the tweeter. It did not fix the issue. I replaced the speaker in the door. That didn't do it either... I thought I must have blown a channel on the head unit. I bought a new one (the exact same model number) I installed it... It still does not work. The phone volume is low & sounds like shit and the front door speaker still does not work.
I would love to hear what you guys have to say about this and I encourage you to make me look like the dumbass that I feel like.

 

Which stereo do you have? Some have an amp under the passenger seat.

 

Thank you for your response!
The unit is a model #A51893

 

It does not appear to have an amp under the seat. Only the duct work for heat.

 

Do you have the Jbl system?

 

No. I do not.

 

I would be extra certain that there isn't an amp hiding under your seat. If there's no amp it should be straight wire between the dash and the door speakers. If you're absolutely positive you don't have the factory external amp, you'd want to get a meter out and yank the head unit, then measure the DC resistance between the two wires that go to the door speakers on the driver's side, then compare that to the passenger side. Major deviations above what the good side is reading would indicate a broken wire, while a significantly lower value could indicate a wire that has rubbed through to the chassis.

 

Okay....
I’m going to pool the passenger seat out so i can pull the carpet back just to be sure there’s not one hiding there. If not, I’ll pull the head unit back out and check the resistance across the speakers. I’ll let you know what i find.

 

Okay....
So I pulled the seat and checked. There is no amp in here. So I took off the drivers door panel and started searching everywhere on the wiring harness and found where the window regulator would rub against the harness every time the window went up or down. I pulled the harness out and found that the positive wire for that speaker had been completely rubbed through. I spliced it and all is good now. Thank you so much for all of your help and just being a good sounding board.