Much of our audio installation work involves distributed sound or 100 volt line. It is a system that is used commonly in public address. In simple terms, the amplifier has a transformer on its output stage that steps the voltage on the speaker line up to a theoretical maximum of 100 volts. At the other end of the line, each speaker also has a transformer that brings the voltage back down again. Operating the speaker line at a higher voltage reduces the power (signal) loss over long distances which is why large installations such as shopping centres and factories are ideal clients for this type of system.
The other advantage of 100v line is that the impedance (resistance) of each speaker is now much higher than a standard speaker at 8 ohms, (a 10 watt 100v line speaker has an impedance of 1000 ohms). This makes 100v line ideal for venues with many speakers such as conference suites and leisure attractions as the wiring is flexible.