Mod a Retro-bit super retro advance adapter so that it outputs video and audio through the SNES and not the included cable.
From https://satoshimatrix.wordpress.com/2013/11/25/retro-bit-super-retro-advance-adapter-review/
Just like the RetroPort and RetroGen, audio and video are not provided through the SNES, but instead an RCA to stereo 3.5mm headphone jack located in the side of the device. This is because unlike the Super GameBoy, RetroBit’s line of adapters do not run Super Nintendo software as a framework for the other platforms. In essence, while the console treats the Super GameBoy as a SNES game, the Retro-Bit Adapter line are not utilizing the SNES PPU at all, therefore there is no video feed to route internally.
It has been suggested that Retro-Bit could have solved this by writing a simple interface program, but that is easier said than done. SNES games were written in low level 65C816 assembly, a language so prone to errors it was abandoned in the mid ’90s and isn’t taught in programming classes anymore. There also aren’t any C or C++ compilers for the highly custom 5A22 cpu Nintendo chose for the SNES.
As is, the included cable is required when using an actual Super Nintendo or Super Famicom. However, this is only true of the original Nintendo hardware and older, non Retro-Bit clone consoles. Newer Retro-Bit clones such as the Retro Duo Portable and the upcoming Super Retro Trio will pass the video feed directly to it’s own video output jacks without the need of the additional cable.