I have the same mixer but it doesn't work how I like. I can't get the phones to output unless I have the main turned up, so I can't go headphones only unless I turn off the speakers independently. Is that how yours works? Right now I have the headphones on main, and the speakers on aux, so I can set their volumes completely independently from the mixer, but the problem is the aux only outputs the left channel to the speakers.

I'd love to send the main to the speakers and headphones on the headphones, but then I have to control the speakers on the mains independently.

How do you have your outputs wired?