I would like to share my solution to the grounding issue in the HX Stomp unit.
First - The problem was a loud buzzing noise when playing the Stomp with headphones. In this setup, there's no grounding through the amp.
One solution is to keep the PL cable connected to the amp, even when the amp is off.
Other solution is to ground the Stomp using the USB port.
I took an old USB cable, cut it and connected the black line to the ground pin of an electrical adapter.
Now when this cable is connected to the Stomp there's independent grounding.
**It's important to only connect the ground pin. Be careful and don't do anything like this if you're not 100% sure what you're doing.
I don't recommend anything, just sharing my own solution.
