Specialization is a guiding principle of modern society and modern audiophilia. We audiophiles split reproduction not only into different components, but those components often consist of separate chassis that are optimized to perform a few functions exceptionally well. Speakers, for instance, can comprise more than one cabinet per channel, and CD and LP playback may require more than one chassis each. Preamps come with outboard power supplies, and mono amplifiers handle only one channel of information at a time. While you can put together a fine audio system that has as few as four separate "boxes" (CD player, integrated amp, and a pair of speakers), you can also buy digital rigs that have that many chassis by themselves.
