The one thing you want to know is does "slave " mean just a power amp or another complete head running preamp and power stages.
A lot of old Ampeg stuff was well set up for daisy chaining amps together. My old Ampeg GT-15C has oulets for an "external amplifier" as well as "external speaker". Very simple and very easy to understand, the term "slave " could mean a power amp in which case plugging in another complete head could damage the preamp or something else in the head plugged into that outlet.....I don't know
For outdoor gigs or when I used to just get nuts and loud , I would run the 235watt Ampeg to power 4 15" Altecs in two cabs, a 200watt Sunn to power either 2 or 4 more 15" EV SROs a set on the other side of the stage, and a 35-40 watt Gibson Atlas aimed at the drummer. It sounded pretty good but make no mistake, I did some damage to my hearing
So , if you are gonna be messing with a bunch of heavy artillery... take some precautions
I SAID TAKE SOME PRECAUTIONS ... sorry , I couldn't hear myself
Rick