Question for the beloved TB'ers -
Currently I am running a head that provides 350 watts at 4ohms to a 4x10 4ohm cab. The head's minimum is 4ohms. I've been wanting to run a 1x18 cab for bigger shows for awhile but haven't been able to. Recently I came across a cheap head

and was wondering if I could use it to drive a separate 18" cab. How would that / would that work? I see that the secondary amp has a "power amp in" 1/4 jack, but I guess i'm not sure where the other end of the cable would go - from the main amps speaker outs?
Thanks and I hope this isn't a dumb question