A power spray system for applying particulate powder material to a substrate includes a volumetric or gravimetric dry material feeding device having an outlet connected to a manifold formed with an internal cavity and a plurality of passageways communicating with the internal cavity. A highly accurately metered quantity of powder is transmitted into the internal cavity of the manifold, which is either applied to the substrate or recirculated back to the powder source. An air amplifier connected to one of the passageways is operable to draw ambient air through a vent passageway into the internal cavity of the manifold to form a stream of air-entrained powder. The powder stream is then drawn out of the internal cavity of the manifold by the air amplifier into a spray gun for discharge onto the substrate. A second air amplifier connected to another passageway formed in the manifold is operated when the first air amplifier in the spray gun is closed to draw the powder entering the manifold into a return line for recirculation back to the powder source.