Before as in next to the battery. Then after the cap too in a distribution block. Thats always nice to have if ever needing 2 or more amps. Then the amp should have an onboard fuse, so 3 fuses for 1 line is well protected. 1 covers battery, 1 covers cap, then 1 covers the amp.
This is what I have, but there are others with their own opinions. So you dont have to put it just like mine, someone will say otherwise, they always do- - - -cheers!