The Pioneer PD-M 90 X is a multi-disc CD player that was designed to provide high-quality audio playback. It supports playing multiple CDs in succession, allowing for an extended listening experience without the need to change discs frequently. The unit features advanced digital-to-analog conversion technology and offers various playback modes, including random and programmed play. It is equipped with a remote control for convenience, and its design typically includes a robust chassis to minimize vibration and enhance sound quality.