It basically converts standard digital signals into ones that can power a loudspeaker or subwoofer. Unfortunately this means that standard analog signals (phonostage, SACD, etc) must first be manually converted to PCM. Included are two pairs of analog inputs (RCA, XLR) that automatically convert signals to 24-bit digital with a user-selectable sample rate of 48, 96, or 129kHz; several digital inputs (AES/EBU, TosLink, TosLink loop); and an RS232 port for external control via a PC. Though highly praised by critics, many purists have been reluctant to invest in an M2. Many are waiting for additional features like HDMI and USB to be incorporated before they make the switch.