Headphone stereo routing

If I connect my monitors to Out 1 and 2, I can dial in a stereo preset by splitting the signal etc.
But with my headphones, it seems that the two outs are just summed to mono and then fed to the headphones. That means that I need to add extra gain blocks and pan left and right to actually get a true stereo out.
Might be a user error, but I can’t find a way to tell my headphones “out 1 is left, out 2 is right” unless I pan through the grid, which is not a sensible workflow.
Any ideas?