At 12 V, the H90’s startup sequence can reach 565 mA, but its nominal function is around 400 mA. The answer to your question depends on whether the Walrus Audio’s internal specs have some headroom added to compensate for component tolerances and temperature variation for less than a minute. This is why Eventide recommends to use 600 mA or more, but you can test powering with one outlet and see how it goes.
