I have my Genesis (model 2) and 32x hooked up with their proper Sega brand A/C adapters.
Pop in a game, turn it on - loud buzzing sound, from the speakers of my television. I removed the 32x, put a game in the Genesis by itself, and no buzzing whatsoever. Crystal clear.
So, it's the 32x. Or is it?
I plugged in a Game Genie, which has an on-off switch with LED (and leeches off the Genesis, I suppose). Loud buzzing with this combination, the same as when the 32x is hooked up.
I've tried swapping the power cables for the 32x and the Genesis, which may or may not be the same voltage (haven't checked) but I still get the same results.
Can't you use a Genesis with a 32x or a Game Genie without an awful loud buzzing sound?
(and just so I don't catch any flack, I'm using the Game Genie to make Contra: Hard Corps playable)