Nope, the box also provides S-Video input. Should give a much better picture when converting from RGB->S-Video using a genlock an then plugging it into the Magic VGA box.
If you want to use RGB without signal conversion, then the XRGB-2 might be something for you. There are also relatively cheap VGA boxes available that provide Component input. Unfortunately, converting from RGB->Component is not easy. But it should theoretically further improve signal quality.
