A schematic of the smps would help. A 50W smps should not have problems with inrush, I believe.
That said, I do not know how inrush is controlled in a switching supply, but in a linear supply a choke-input filter can be used to reduce inrush. Other ways are to include a high-power resistor in series with the transformer's primary and then bypass or short it out with a timed relay. So when powered up the resistor is in circuit and controls the primary current, and after a few milliseconds delay, when the transformer has settled, the relay shorts out the resistor to allow full primary current.
