Anyway, who knows a good source for a real Famicom?
From that wiki entry:
These [two sound] pins were removed from the cartridge port of the NES, and relocated to the bottom expansion port.
Hrm, how adventurous do you feel?
Quick update: Somebody else felt adventurous enough. Still reading.
Next question, and I'd look this up if I weren't babysitting a raving baby, is whether my top-loader NES (thanks, Ruffin!) has the appropriate pins. No expansion port, right...?
I moddified mine.