Thanks for the help here, everyone.
Even with my Strymon Zuma I use a combined lower lead for the H9 to double the current capability. In a side note I used a triple for the Line 6 HX effects so, as others suggest, these bits of kit are very power hungry.
I’m going to try this and see how it goes! I’ve ordered the Eventide power supply so if the power cuts out again even with 1000mA, I’ll try it with that and see if it fixes the issue.