Hi audiofan,
Denon stereo receivers have been high-quality for years, and will drive the M3ti's or M60s easily, the latter within the limitations of room volume and the Denon's rated power output. The latter may well be closer to its specs than many multichannel A/V receivers, which are often rated with just one channel driven, which can be very misleading in terms of the receiver's real power output driving five or more channels.
You can use an inexpensive CD player's analog output jacks to connect to the Denon. The CD player's internal D/A (digital-to-analog) converters will be indistinguishable from other brands (it's a mature technology) except with test signals auditioned at extremely high level. Even those in inexpensive Panasonic or Sony portables are excellent these days.
Likewise, you would have to use a DVD player's analog stereo audio output jacks to play back CDs or DVD audio in stereo.
Stereo receivers do not have digital inputs because the vast majority of customers want Dolby Digital/dts 5.1-channel playback for movie and DVD surround sound. The digital circuitry in multichannel A/V receivers will also decode stereo CDs into a 5.1-channel configuration with Dolby Pro LogicII. With classical, jazz and other acoustic recordings, as well as some pop/rock material, this can be a huge enhancement in listening pleasure and realism over 2-channel stereo.
Regards,
