2006 XC70 rear fuse pinout

[jdell]

I’m trying to do a simple amplifier install while keeping factory amplifier and head unit. I have been trying to determine if there is a switched source in one of the fuses in the rear panel that I can tie into for the line converter that I am going to use, but cannot find anything.
I’ve seen people say they’ve taken switched power from the 12V in the rear armrest, but that seems silly if there’s something in that box it could be taken from. Any input is greatly appreciated, thanks!