In reply to:

Is there a safety issue with using a cheater plug long term? I REALLY don't want to burn my s-i-l's house down.


Not so much a fire hazard as a shock hazard... like if the owner of the Tigger toy pours a pitcher of iced tea into the port and starts doing the 115v mambo. Try the ground break, see if it solves the hum - tells you whether or not it's a ground issue, it could just be a noisy amplifier circuit, since it's not exactly a high-end piece of technology.

Bren R.