Here you go. https://comtalkinc.com/page-plus-controller-406914598-p-976.html Scroll down to the documentation PDFs

The D20 is 20w total so all call (worst case) means that all speakers should total less than 20w. You can use normal 70v speakers. I agree with you about the 24ga wire. I would like to see 18ga. Maybe that's the reason for two pair per zone- are they doubled up?

-Hal



CALIFORNIA PROPOSITION 65 WARNING: Some comments made by me are known to the State of California to cause irreversible brain damage and serious mental disorders leading to confinement.