Toroidal transformers has no airgap like old E I laminations or c-cores which means they have a very small stray field.
A gap will minimize the DC saturation, so yes DC is bad but how much before the toroid starts humming from saturation. As the transformer is very heavy it is possible it may have shifted in transit.
Is it epoxy potted or mounted on a rubber disc?
Make sure nothing is connected to the center bolt as this could make a secondary turn on the toroid, inducing a load or a voltage. Been there...
A gap will minimize the DC saturation, so yes DC is bad but how much before the toroid starts humming from saturation. As the transformer is very heavy it is possible it may have shifted in transit.
Is it epoxy potted or mounted on a rubber disc?
Make sure nothing is connected to the center bolt as this could make a secondary turn on the toroid, inducing a load or a voltage. Been there...