Built-in power amplifiers save space and eliminate the need to connect Audioengine 5+ to a stereo receiver or external power amp. Simply plug the left speaker into an AC outlet and connect the included speaker wire from the left to right speaker. All internal components of the A5+ are tuned together, providing a more efficient system requiring less power than passive speakers and amplifiers. With superior stereo separation and incredible imaging, A5+ has a clear sonic advantage over boomboxes or all-in-one systems.