Cut an Ikea table leg to desired length and mount upside-down and screwed into the desk top.

The large printed part fits (very) snugly into the leg tube and makes for a solid mount for a desktop speaker stand.  Route the speaker wire through the rear hole for some measure of security (example: standing desk, in case wire gets pulled when raising desk, to avoid pulling the speaker off the stand).  Smaller part is washer which uses M2 screw and heatset nut to hold the speaker.  (Stand is slanted forward to point the speaker flat)

I made this for Logitech Z2300 speakers