That's a PA system. Anyways, which model did you get? Lucky to get that thing huh?
Assuming you have the C10/C20 models, here's a simple way to use that thingie.
From any low level output (say from your pc soundcard), connect the cable from that output to the aux input of the amplifier.
For the speaker, hmm, if you are using 4 ohm speaker, then connect the + the the 4 ohm terminal and the other to the gnd terminal.
And then plug in the socket, turn on, and there you'll go
From my experience (using other brand of PA amplifier) the 25V and 70V terminals are only for use with speakers with built in transformer (PA system speakers).
By the way, i never see any PA amplifier using screw as an interface for the microphone.
One more, just in case smokes come out from that PA, don't throw it away. Give it to me bah :twisted: