Why? Oh why?
That's why. This mod appeared on a Chinese D.I.Y. board, so just go with it. As website Technabob points out, the mod integrates the boombox's CD tray with the Dreamcast's CD-Rom drive. In front, the Dreamcast's four controller ports find a new home.
The Dreamcast was launched in Japan in November 1998 and later discontinued in 2002.
Watch the modded boombox in action. (Might want to turn the sound down. Squeaky camera noise!)