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Is it possible to allow for a mode to record audio in which the PPU buzzing wouldn't affect the quality of the music? A recording mode in which the PPU is shut off before the song? A way to shut the PPU on or off during a NSF? There is a buzz when recording an NSF that just isn't very nice coming from the PPU.

Perhaps you could install a switch between the PPU's composite output pin and the circuit board. Otherwise, the video signal leaks into audio. This is a problem I've encountered when recording any game system.

I would imagine that if the palette is filled with blacker than black ($0D) entries, there would be less video signal to leak.

You can try this. Push start to shut off the display.
http://home.comcast.net/~olimar/nsf_ppuoff.zip
(copy to the POWERPAK\ dir)

Thanks! I'll give this a shot.

Edit: Here is an amplified clip of a blank NSF. At around 4 seconds I turn the PPU off. There is a marginable amount of difference, but there is still a lot of buzz that I cannot account for. Any ideas?

The PPU can't be turned off. It's always generating a video signal. That's why I think disconnecting the pin is the only (possible) way.

So I've tried disconnecting the Vout (pin 21) on the PPU and the buzzing still remains. I had it working for a short while but then when I went to install the switch, it retuned and remained. Any thought as to what I need to do to get the buzzing to leave?