For audio distribution on long-speaker lines are different techniques used for decades instead of the usual standards in audio engineering.
Within the world of broadcasting and evacuation we have to deal with the fact that a large number of speakers are driven by the amplifier. It is not possible for a large number of speakers just to connect to the output of an amplifier and there is also a technology developed in the past where we use a high voltage output of 100 Volt.
In addition, by this choice the line current decreased and thus the losses of the cable also dropped significantly.
Without going in the details of the technique, it is possible in this manner to put a large number of speakers parallel on such a line. Virtually every manufacturer of alarm systems works with this technology.
This technology is reliable and easy to produce. The quality of the sound is almost unchanged, compared to conventional techniques.