Do it the other way arround. Take a very bad situation. Spike damage.
Azalgor does Auto-Hits of 7-8k on Plate (according to bosskillers, we have our Bear tank him, but lets take this) and a cleave of about 10k.
I took 20.000 Raw Damage and 27500 Raw Damage for those attacks.
(Simplified. No -Blocking and no -6% Damage. Should make no difference

)
%Reduction for 73 = (Armor / (Armor + 11960)) * 100
20000 = 0,626 Reduktion
20240 = 0,629 Reduktion
With 20k Armor (assum you chuck potions for extra armor..)
7484 Auto + 10291 Cleave (Azalgor Parries) + (hasted) 7484 Auto = 25260 (hope you have some HoTs ticking..)
Now you have 20.240 Armor
7429 Auto + 10214 Cleave (Azalgor Parries) + (hasted) 7429 = 25071
Which is about 188 Damage less.
So, on average, you get a lot less damage over a long fight (where the extra 10 Stamina does...nothing..) and when it really counts: you survive more (more EH) with 240 Armor.
+10 Stamina is just if you feel good about huge HP numbers. But then you will also socket Blue +15 Sta Gems in all your gear and feel good about
