I just bought a rather nice electric guitar kit for a hundred bucks
that came with a 10 watt amplifier. The guitar is pretty nice but the
amplifier has a rather nasty hum. I thought it was a vacuum tube amp
but found out it actually has transistors-- or an IC amplifier-- I'm
not sure.

The power transformer is pretty close to the circuit and the wires for
it were tangled with some of the speaker wires. When I untangled them,
the hum disappeared... until I plugged into the jack the guitar cable,
then the hum came back. Does anybody have any suggestions for getting
rid of this hum problem?

Ron