I suspect that most often it's not a phantom power but a ground issue.
The two devices I still use regularly (an old Zoom G3 for small acoustic guitar gigs and a GT-1000 as the "brain" of my main pedalboard) have dedicated ground lifts (the GT even comes with various settings separated for both the 1/4 and XLR outs, which is just excellent). And I've never been running into any issue with them ever. They just don't care whether there's PP or not. Which is what I defenitely expect things to be like. I mean, why would a modeler come with a balanced XLR out and I'd still have to cable up a DI box, PP blocker or whatsoever? Just doesn't make any sense.