I've seen arrays of passive speaker boxes (high output passive professional PA speakers) that were connected to each other and only the last (or first) one was connected to the power amplifier (a very high power amplifier in that case). The speaker cabiners had the sockets labelled IN and OUT, which means they had been designed for this sort of connection.
The question: I wonder whether the same setup - multiple speakers hooked on single amp output - is possible with standard consumer home audio systems (as my Cantons dont't have the OUT connectors). I'm only interested in the technical aspects, not in how the fidelity may degrade (I only use coat hangers to connect my speakers).
I'm not very well educated in this field, so I'd like to provide some of reasoning I'd already done, in case there is something to correct in there, too. I understand that one should never connect a speaker box of impedance lower than that for which the amplifier is designed (so you can connect 8 Ohm speaker to 4 Ohm rated amp but not the other way around). I'd count that impedance behaves quite like resistance in that, that if I connect the speakers in parallel, I'd end up with half total impedance and would need a 4 Ohm rated amp for a pair of 8 Ohm rated speakers. With three of them, I'd be down to 2,5 Ohm rated amp for 8 Ohm speaker boxes. With speakers connected in series, I'd need an amp power rated roughly equal to the speaker power ratings combined but won't need to worry about the impedance (as long as the speakers are same or higher impedance than amp rating). For simplicity, I use sets of same speakers (make, model, power rating, impedance) here because that is what interests me. My amps are D-class.