Compare the amplifier’s rated power per channel at 4 ohms with each speaker’s continuous power-handling rating, using the same measurement basis when available. Check that the speaker wiring keeps the total load within the amplifier’s supported impedance, and set levels to avoid overdriving the speakers.

A 4-ohm amplifier can work with speakers at other impedances when its specifications list those loads as supported. Check the amplifier’s rated impedance range before connecting speakers, since a load below its minimum rating can cause the amplifier to overheat or shut down.

When you connect 4-ohm speakers in parallel, the combined impedance drops, so two speakers present a 2-ohm load that may exceed the amplifier channel’s rating. Check the amplifier’s minimum supported impedance and the speakers’ wiring configuration before connecting multiple speakers, since series wiring raises the combined impedance.

A 4-ohm amplifier drives low-impedance speakers directly, making it a common fit for installations with shorter cable runs and a smaller number of speakers. A 70V/100V amplifier uses a constant-voltage output and transformer-equipped speakers, which can simplify wiring for multiple speakers across longer runs in commercial audio systems.