MIC MORSEL: YOUR AUDIO CABLES AND A.C. POWER

If you play amplified harmonica, sooner or later you'll encounter unwanted noise in your sonic signal path -no matter how carefully you've chosen and matched your gear and your wires. Very often the source / cause is INDUCTANCE.
INDUCTANCE is the influence of one electromagnetic field upon another. The culprit in this case is the interaction between your gear and A.C. (Alternating Current) electricity -common household power.
The best way to avoid the negative effects of A.C. INDUCTANCE on your D.C. (Direct Current) gear is to know what NOT to do...
DO NOT bundle or run audio cables together with A.C. cables. This includes zipcord extensions. Try to cross A.C.and D.C. wires at right angles to minimize their interaction.
DO NOT run your gear off a dimmer circuit or in conjunction with a light dimmer circuit. A separate circuit breaker leg is preferable.
DO NOT operate your gear in close proximity with fluorescent light fixtures -or on the same circuit if you can help it. Their transformers can cause real problems.
DO NOT use any "wall warts" with your audio gear that are not 'regulated power supplies'. That goes for the ones replacing 9VDC batteries in your stomp box effects pedals. Sometimes they're referred to as "filtered" power...
HEY! You don't have to be a politician to learn how to use power responsibly...