AV Famicom - missing audio channel

[lackattack]

Hi all, great site here.

I have an issue with my AV Famicom. I had it modded with an NESRGB board several years ago. When using an N8 Everdrive Pro, I am clearly missing an audio channel. I've read several posts here on the topic, but wanted to make sure I was headed down the right path.

Here is a clip of my audio missing a channel on my AV Famicom on N8 Everdrive Pro (can hear it when Mario picks up an egg): https://clips.twitch.tv/FlaccidRelentlessZucchiniPipeHype-8_W7NAMoVfThut86

Here is a clip of expected audio from the same AV famicom but playing on the SMB2 cart instead of Everdrive.: https://clips.twitch.tv/SquareTransparentHyenaRlyTho-4qe8RhXtB90HxYTX

I use Retrovision Component cables through the AV out port on the AV famicom. I use a model 1 genesis AC adapter, and have replaced the capacitors, but it did not fix the issue.

Anyone have any guidance? Thanks!

[P]

The NES APU has 5 channels named A to E:
A: square wave (AKA pulse)
B: square wave (AKA pulse)
C: triangle wave
D: noise
E: DPCM (AKA DMC or Delta-Mod)

This game uses all of them, the main BGM uses both squares for melody, the triangle for bass and the noise for the drums. In sound effects it is using one of the squares and sometimes the DPCM (the scream Catherine/Birdo is doing when hit).
It sounds like you have both the square channels but you are at least missing the DPCM channel as there is no scream.
It is very easy to test the other channels in this game since the game mutes the melody (squares) when you pause the game, while the bass and drums keeps playing.

Now I have no idea how NESRGB works regarding audio, but it kind of sounds like whoever did the NESRGB-mod didn't wire the CPU pin AD2 correctly or something like that. The two square channels are output from AD1 and triangle, noise and DPCM are output from AD2.