Hudsonsoft, famous for the Bomberman series, released the Joycard Sansui SSS for the NES sometime in the late 80s. It is a heavy controller, weighing in at almost double a standard NES controller, and designed to be more similar to a Famicom controller than an NES controller it has a very special aspect to make it a must have for any NES collector. The Sansui SSS is heavier than a standard controller because it has sound processing hardware inside of the controller. By plugging the red RCA plug into the red port on the side of the NES and headphones into the controller itself, you will hear pseudo stereo sound from your mono NES. It is not true stereo - it takes the mono sound and based on where your character is on the screen is which ear the sound will be processed to.
It also hosts a sturdier Dpad and buttons than any other third party controller. And turbo sliders similar to those on a PC Engine controller.
Due to its use of the RCA port, the Sansui SSS is incompatible with the Model 2 NES, all Famicoms, and most Clone consoles.