Help with UR44 Connections


I see this is quite a big forum so I apologize if my question is already answered somewhere, I did some research and couldn’t find exactly what I am asking here.

I have a UR44 USB audio interface and after reading its documentation
I have some questions. I will appreciate it if you could help me to better understand the following:

  1. Connecting my Casio PX760 to this device’s analog inputs (I know I can connect it through USB to use as a controller for DAW but here I am considering a different scenario):
    The documentation mentioned “digital instrument” in three places: [MIC/HI-Z 1/2] jacks at the front, [MIC/LINE 3/4] jacks at the front and [LINE INPUT 5/6] jacks at the back. But Casio PX760 doesn’t have a “line level” outputs, it has only headphone outputs. So what analog input of UR44 is most suitable for this connection?

  2. Connecting my JBL LSR305 powered monitors to this device’s analog outputs.
    The document shows “monitor speakers” connected to “Main output”. Does it apply also to powered monitors? In what cases would I use “Line output” connectors? Also, these monitors have an input sensitivity switch with two positions: -10 dBV and +4 dBu. Can you please help me to determine what kind of output I should use to connect my speakers and whether I need to set the input sensitivity switch +4 dBu setting.

Thank you very much!