Non selected staves are played to MIDI

I'm using my keyboard through MIDI to both input notes and listen my score (*).

When I select a part of my score and play it, the normal behaviour is that it plays only the selected part.

This is not the case with MID I output: all the staves are played.

Anyway to configure this ?

(*)working at night with my headphone, so I can only wear one headphone at the time: the one connected to my keyboard.