Radio Harness Fuse/AMP ratings?

[BGChicago]

I am planning to upgrade the Sport Basic stereo to Tablet as a head unit, 1 Din basic head unit as a pre-amp and a small 4x45/50 amp in the remaining space in the dash (either the Alpine 445a/u or Clarion 1410).
If I go with the Alpine route, the 445a harness directly to an Alpine radio and doesn't need extra power harness IF the original on is rated at least 15 AMPs.

So, does anyone knows what is the power supplied to the original radio rated? Perhaps, the fuse rating?

I checked all diagrams and I couldn't find this. My concern is that I don't want to pull an extra wire from the battery.

 

[BGChicago]

I found some more info, but still need extra help: It seems like there are 3 Audio fuses - #38 AUDIO2 - 7.5A, #43 BOSE - 25A, and #44 AUDIO1 - 15A. The Bose fuse doesn't apply to me since I don't have the Bose system.

What is weird though is that any of the 2 AUDIO fuses turn off my radio when unplugged. Anyone knows what fuse is for what?

 

[BGChicago]

Another question I have: I know that the Bose amp should be somewhere behind/under the passenger's site compartment. I open the are up today with hope to see the harness for it (since it has 25 amp fuse it will be sufficient for my need) but I couldn't find it. I guess the final piece of the harness isn't installed on the non Bose models but it should have a coupler somewhere in the cabin. Anyone knows where that connector is?