I am trying to help my friend buy a receiver/amplifier for his home audio setup.
He has 8 ceiling speakers with 4 wires (red,black,green,white) and 4 wall speaker with 2 wires (red,black) throughout the house. The ones with 2 wires produce a crackle when attached to a AA battery and have a DC resistance. The 4 wire ones have a small DC resistance, and do not crackle (although maybe the speaker is out of earshot).
Based on these observations, I think the ceiling speakers are 70V because based on this forum, the DC resistance would be high due to 70V speakers having a transformer.
I think the wall speakers are 2/4/8 ohms because they have a low resistance, but the multimeter he is using is not good so I don't have a precise measurement.
Is this assessment correct?
If so, would this mixing amp work?