Do you have any pictures of the phenomenon occuring? Which firmware version?
Difficult to take a picture of it. If you play RC Pro Am II and just start the first race, turn scan lines off, and look at the green field. Even when the game is paused there is a ton of faint visual noise. In the picture the green should be a single solid color. Instead there are bright and low spots all over the place constantly shifting. It is not JPEG compression, that is how it actually looks on the TV. I took a video that shows the flickering visual noise. It is quite easy to see with the human eye, but cameras have a hard time capturing it. This does not occur with N64 titles.
Video: https://drive.google.com/file/d/0B695Hc ... sp=sharing
Have you updated to 1.03 already?
I was on 1.02. I updated to 1.03 after reviewing the changlog (which specifically references audio issues, hah!) and it certainly did resolve the audio issues I had with NES games. Thanks for the heads up!
That said I do notice now when turning the N64 on there is a soft pop (common when starting some games) but then a chirp sound a second later as the menu comes on screen. It did not chirp like that before the firmware update. Not a huge deal, but thought I should mention it.