If you are a purist who wants the physical paper manual:
These are crowd-sourced databases for vintage audio gear.
The is a compact CD receiver system released in the late 1990s as part of Denon's successful "M series" of micro hi-fi systems. While the physical user manual is often sold as a vintage document on sites like eBay , digital versions and technical summaries are available through community archives. Key Features & Specifications
Here are the technical specifications of the Denon UD-M3:
If you need the complete technical documentation or original operating instructions, you can access them through several reputable archives: