Sorry for the delayed response I have overlooked your message somehow.
I made a test with full scale signal, I had no problem with this signal. I made a measurement on the outputs on the back panel.
This is true if you use full scale signal on each output that may overload the internal mixer.
You didn’t describe where do you experienced that clipping? If only in the headphones output you may need to reduce the levels in the mixer in uTool (let say -9dB on each track)