I want to know if it will stack with my others or not.
Yes. Currently Diablo 3 does not have any inventory charms like Diablo 2 had. You must equip all items to gain the passive effects.
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As a side note to the stacking bit. The benefits do not stack, if you equip an amulet that gives passive X. Equipping passive as one of your 4 passives will have no effect (if it will even let you equip it at all). – JekwA Jul 13 '15 at 21:11