Bill, a normal set-up would be;
1-Sound source (keyboard) into Computer, unless you want to EQ the sound.
2-Then it would be Sound source into Mixer or EQ the to the Computer
3-From the computer to the X2300

In this way you will always hear what the recorder on the computer hears.

I do not like want comes from the head phone outs., that’s not what they are meant for – possible distortion.

Another thought is line out to the mixer or computer -- and controlling the record volume with the computer. Then the main outs of the keyboard to the Z2300.

Line out is pure out with no volume control.

John C.