If you are looking at your UDM3 right now, here is what every knob and button does. This is the most requested section for a reference.
: Install R03/AAA batteries into the remote control unit (RC-877). denon udm3 manual user manual top
While the prohibits user modifications, enthusiasts have found life-improving tweaks: If you are looking at your UDM3 right
: A specialized site for free service manual downloads, useful for DIY repairs. Key Specifications & Features denon udm3 manual user manual top