Magic items get a Reflex save (DC 20) to survive, using their own saves or those of the wearer, whichever is better. IIRC, an unconscious (ie helpless) person is unable to make Reflex saves, so the objects would use their own saves
The armor and shield in your example have save bonuses of +3. (A magic item's save bonuses are equal to 2 + half its caster level. Any +1 armor has a minimum caster level of 3.) So, each would need to roll a 17 or higher to survive.