Did you know that the Super Game Boy is not perfectly in tune?
"The original Super Game Boy is known to play the game program and its audio 2.4% faster than other Game Boy hardware. This is due to the use of the Super NES's clock speed divided by 5 (which ends up being 4.295 MHz), instead of 4.194 MHz." - Wikipedia.com
We're now developing a simple kit that allows you to tune the SGB to the correct speed. Here's a photo of a quick prototype using original DMG parts. The kit will have smaller SMT parts. All you will need to do is lift two pins from the SGB processor off of the PCB and solder 3 wires.