Can some one tell me what this is?

Hi.
I have a 2002 limited 4runner I recently bought and I need help identifying an electrical part.

Ive attached pics in hopes some one can tell me what this box is? It's mounted behind the radio close to or possibly on the firewall. There is a 12 wire plug coming out of it and was connected to a 10 wire plug coming out of my after market head unit. (im guessing the 10 wire plug is part of a wiring kit). To 10 wire plug has wires for 12v cont, 2 x 12v remote, ground, 2 power ant leads, 4 rca outputs (front and rear, right and left).

I cant find this box in my chiltens and dont have a fsm. Could it be an external amp for the radio. If it is I want to bypass it so I can install an after market amp.

Can anyone identify this part for me? Does anyone have a wiring diagram or schematic of the thing?
Can I remove it completely?

 

I forgot to thank you guys for any help I might get with this post.
Thank you

 

Pretty sure it is a amplifier.

 

Thats the stock amp, I believe any aftermarket head unit will bypass it and use the wiring harness plugging into the back of the amp to splice into the new head unit.

 

Thanks guys. I thought it was the stock amp but couldnt find anything confirming it. I only have a chiltons book on the truck. I want to find a factory service manual on it but Im stuck with chiltens for now. Chiltens gives me the 4runner, t100 and tacoma in one book and the 4runner info being the least info in it.
Thanks for the help.