Here was the response from Neural:
We tested to put just a gain block and start raising the level. Headphones start to clip before the red light on the lane output lights up. XLR outs have more headroom and start clipping much later. With 16 ohms headphones, this can be more noticeable.
The headphones’ output has an internal gain stage of +6dB. This could explain why you feel that the signal has more headroom while using the XLR outputs. Using the Headphones level between 0dB and -3dB should be enough to avoid internal clipping. Using Quad Cortex with the Volume wheel at 100 is also safe. Please, double-check if the clipping is gone after doing this.
Notice you can boost the output blocks by accessing the LANE OUTPUT CONTROL from the grid (tap and hold the output blocks to access this menu). After that, please boost the Headphones LEVEL from the I/O Settings as much as you need and check.
Let us know how this goes!"