I had the F-Labo kit done by Drakon here for my AV Famicom and I couldn't be happier. Besides the incredible picture quality, the stereo mod is superb.
Here's an interesting device I bought called the ENIO EXP:
It pops right into the expansion port of your toaster (finally, a use for that port!). Not only do you now get expanded audio for your Famicom games, but it also gives you the Famicom accessory port for your NES toaster so you can use the Famicom computer keyboard, the Famicom 3-D glasses, etc.
Since I know Drakon is experienced with finding the best methods of doing things, I figured I'd post about this here. There's a million guides online on how to do the "stereo" mod for the NES, but the instructions are wild and varying. Some call for two potentiometers, some call for one. Some call for resistors, some don't. Some call for capacitors, some don't. I can't find a solid, definitive guide for the mod.
I was also wondering if it would sound as good as my Drakon-modded AV Famicom? That thing puts out some incredible sound, but I am assuming the F-Labo is to thank for most of that. Is there any way to get F-Labo quality "stereo" in my toaster, without actually buying an F-Labo?