Game Boy

The Game Boy Classic came with a single mono speaker, even though many of its games were written for stereo sound, so the console never really did justice to its own soundtracks. The American manufacturer Nuby answered this with an attachable stereo speaker that plugs into the headphone socket, the one output that carried the native stereo signal, with a built-in amplifier for a fuller sound.

Nuby was not alone in spotting the gap. The collection also holds the Japanese Sunsoft Sound Boy, which used almost the same approach, Nintendo's own DMG-02 stereo headphones, and FM radio add-ons such as the BigBen FM Gameball and the Beeshu GameTunes tuner.