Yeah i've read about the cotton balls and I believe you that it works quite well, i'm just trying to think of a more elegant way of doing it. Plus if i wanted to change between sound and no sound i'd have to keep unscrewing the pommel and taking the cotton balls out. It may require more work but I think if I can pull it off it'll work great.
You could also wire a very small sliding switch to the red speaker wire and tuck it in under the Obsidian board... maybe on the opposite side of the USB port. Sure, you'd have to slide out the battery pack to use it, but you'd certainly get what you were looking for with almost zero effort or cost.