Could be the signal. What kind of input are you using?
It is! The SNES was wavy as all get out, and so was my 64. They were both using the same model S-Video connector I bought on eBay. Signal was bad using either the S-Video hookup or the composite, regardless of the TV input I was using. My PS2 seemed fine though. I dug out an old official Nintendo A/V composite cable and it cleared right up.
Thanks so much for guiding me in that direction. Guess I need to find a good SNES/N64 S-Video connector now. Can anyone recommend one?