Have you actually added up the max current draw for your pedals compared to your power supply? Depending on what else you're using, it's likely the H9 is at the high end of the power usage for your signal chain.

If you have a multimeter, you can also check that the voltage your power supply is providing is stable; overdrawn power supplies and underpowered pedals can appear to function normally but misbehave in subtle ways (like noise).