Passive speakers are those that must be connected to an amplifier to make them sound. When choosing one or the other, we must take into account several factors: the size of the room in which we are going to use them, the sound level we want to achieve, etc. Depending on the size, we will also choose the number and type of speakers and the power required. Next, the necessary amplifiers will be chosen to connect the chosen speakers. For this, it will be necessary to calculate the necessary power to the resulting impedance.
For example, if we choose 4 speakers of 200 W each to 8 Ohms for our room of 100 square meters, and we connect them in parallel (two speakers to each channel of the amplifier) we must use a power amplifier that is capable of delivering at least 400 Wrms onto 4 Ohms (which is the resulting impedance of putting 2 8 Ohm speakers in parallel).
As always, do not hesitate to contact us for advice on your needs.