The foundation of the MCR-332s excellent audio performance is a Yamaha-developed digital amp that provides smooth, unforced sound output. The receivers separate digital & analog low-noise circuitry ensures thoroughly high sound quality, which is delivered by new-design speakers. A USB (Universal Serial Bus) terminal on the top of the unit makes it quick & easy to plug in an iPad or other USB (Universal Serial Bus) device. The digital connection permits fast, loss-free signal transmission. The iPhone/iPod dedicated dock provides a digital connection, which means that the digital signal from the iPhone/iPod is transmitted directly to the receiver. This minimizes noise interference & allows use of the MCR-332 DAC, rather than the /iPhone/iPod DAC, resulting in more precise sound reproduction. The aluminium hairline finish of the front panel & knobs also contributes to the over high class appearance of the system. The subwoofer out terminals lets you connect a subwoofer to enjoy enhanced bass power & response. The AUX-in terminal allows connection of other audio components.