The guy who made this video is a noob (like most people on the internets). And to make things worse this guy can't even figure out how to buy and install a 15$ usb capture device to capture the audio. I've built every nes / famicom audio circuit available out there and the best one I found came with the upgrade kit for the av famicom. All the other circuits could mix in the famicom audio and get pseudo stereo sound and even could increase the bass. But the sound in common audio circuits were always muffled and didn't have a large range of audio. The av famicom audio upgrade circuit increases the bass but maintains a very larger audio range. Just like tiidos amazing sega genesis crystal clear audio mod the av famicom audio circuit opens up the entire audio range. But unlike tiidos amazing circuit the av famicom circuit increases the bass to the proper level while maintaining a full range of audio. In other audio circuits out there you could increase the bass but then the bass level would sound off and everything would sound muffled because of the overpowering bass. Also this guys little nes switch isn't for mixing only vrc6 games it's for any famicom cart with upgraded audio inside which can also be the vrc7, the chip used in gimmick and possibly more.
I just visited the super kevio official website and you can see he's catering to complete idiots who know nothing about the hardware. His website is very pretty, simple, easy to use, and offers information that makes his mods sound awesome. Here's a quote from the kevio website:
"If you are only getting one mod, this is the one to get! The standard NES audio is upgraded to true stereo output."
There's no such thing as true stereo sound from a NES. No game was programmed to make use of and stereo separation because the nes / famicom were always mono. The only reason the fake stereo sound mod exists is because the nes cpu outputs audio on two pins and each pin contains half of the sound channels. This simple mod has been around forever and it's nothing in comparison to the av famicom kits I order from japan.
There's a lot of guys out there offering simple cosmetic mods to a system that make it look pretty like lighting up logos and different coloured LEDS. But when it comes to actual internal upgrades the circuits these "modders" use extremely simple circuits (like all the mods they offer) which aren't good quality. One of my clients mailed me his toaster NES that had been rgb and stereo modded by some other dude. This client paid me to redo the entire system as the sound quality was nothing special and the video was full of jailbar interference. What's unbelievable is that the jailbars were caused by cruddy modding and shouldn't have even been there. The reason why this toaster wasn't working right is because whoever built it (acem77 the f#cking idiot markered his usename all over the inside of the case) didn't actually come up with proper circuits. Instead acem77 just copied the moosmann guide-o except the amp acem77 designed and signed his name all over was way more simple than the one on the guide and not powerful enough. I was the first person to really try to genuinely get everything stable and functioning how it should look and sound instead of just copying some cheap simple guide posted on the internet by someone else. This magical kevio system is the common simple mod which is far from as good as it could sound.