I was hoping everyone assumed I was talking about the distribution block. Thats y I said "for the sub amp" not "in"

 

So to sort everything out.

For my Kenwood KAC-9102D, ( two "30" fuses on back of amp ) I should use a 40A fuse in the distro. Block.
For my Legacy La-290, ( one "10" fuse on back of amp ) I should also use a 40A fuse in the distro Block.
For my Pyramid CR-74G Crossover unit, it has a built in tube fuse, but I can not find the size. I also wired that up to my distro. Block, should a 40A fuse be used aswell?
Lastly, for the Main Power Feed, I should use an 80-120A fuse.

 

the kenwood is what an 1800W max amp... i would use maby an 80 amper.
hard to tell cuz its kenwood.