In speaking with the BBC on Friday, representatives for the world's largest software maker stopped short of flatly denying the reports, saying only that the company did not "have anything to announce at this time".
Over the past week, unnamed music industry executives have told the both Reuters and the Associated Press that they have received briefings about the product.
Both reports said the proposed device would play digital music and video files and carry wireless technology that would enable users to download content without the need to connect to a computer.
Microsoft is also said to be developing a software rival to Apple's iTunes that would form the foundation for its own integrated system of digital media players and online download service.
Nate Elliott, digital home analyst at Jupiter Research, told the BBC that if Microsoft were planning an digital media player it would be because of "frustration."
"Microsoft and its partners have made no significant headway into Apple's dominance of the market," he said. "Microsoft is not a hardware company but they have shown that when they really want to make a success of something they are willing to do it themselves."