Thanks man, i was burning my noob brain with numbers.
I want to use coa (174str req) on an lvl 99 paladin V/T (25str start) with enigma (+74str) archon plate (103str req), anni (20str), torch (20str)
Str needed from expensive amu+ring: 174-74-25-20-20= 35str needed
I am poor so i prefer to stat str and pay less.
With ap you can stat max: 103-74-25-1=3str
LOL thats nearly nothing

So i must get at least 32str in amu+ring. Are my numbers right?