NUX MLB noisy through headphones

To other owners:

is it always this noisy through headphones? I just bought it as a travel headphone amp, but using it with a pair of headphones gives a pretty big noise floor.

When I have it connected to a laptop it is dead silent. Which I assume means that it is grounded through the usb and the laptop that is plugged into the (European) outlet.

unfortunately I will be travelling, and all my powersupplies that are easy to bring are one spot type cables , that are not grounded I guess.

trying to figure out if you have the same experience and a ‘proper’ plug will fix it, or that the pedal has known issues