I haven't heard of anyone doing it, though it's theoretically possible. The XLR out has an impedance of 80 ohms. That means you wouldn't want to use 300 ohm Sennheisers with it, as the damping factor would be too low. But with 600 ohm Beyers and such it would come very close to the ideal minimum damping factor of 8. So it would probably work just fine. Any benefit compared to the front panel headphone jack? Doubtful but you never know.