Hi philh0954,
Strymon doesn’t sell a current doubler cable, so I would go with the Voodoo Lab/Vertex combination of products. Together they will allow you to power the H90 from your Zuma. The problem with the Strymon adapter is that it’s female on one side, so it would only work for a pedal that only needs the power from ONE outlet and in conjunction with one of their barrel cables. That’s not the case with the H90. Hope that clarifies things for you.
