Unlike powered speakers (such as computer speakers, powered monitors, and speaker docks), which have built-in amplification, passive speakers require pre-amplification to adjust the signal’s volume to desired levels, and power amplification to further boost the signal so that it’s strong enough to make the speakers move and produce sound. (If you don’t have an old set of speakers, there’s a huge variety of unpowered speakers available that offer impressive performance, beauty, or value-or some combination of the three.) All that’s required to get your old (or new) speakers making music is an audio source (an iPod, iOS device, Apple TV, Airport Express, Bluetooth audio receiver, old CD or DVD player, or computer) and an integrated amplifier or stereo receiver. Such speakers can be repurposed to build your own iPod stereo or AirPlay audio system, but they can also be used to put together a quality desktop stereo.
I suspect a substantial number of people have an old pair of speakers sitting in storage: hand-me-downs from a family member, perhaps, or the remnants of a stereo of their youth.
